ESPN Tennis

Pete Sampras has said that tennis is at its best, most appealing, and most resonant when there's a genuine rivalry at the top of the game, and we've been lucky to live in an era of great one-on-one matchups.

This goes all the way back to those first meetings between Chris Evert and Martina Navratilova, in what would become the closest we'll ever witness to a perfect rivalry. But admit it, this Roger Federer versus Rafael Nadal stuff isn't half-bad, either, and for a while that Kim Clijsters versus Justine Henin Belgian border war also was riveting. But what will the future bring in the way of rivalries? Here are a few that may develop, or catch fire, in the near future:

Robin Soderling leads Tomas Berdych (6-3): Most rivalries are intriguing because of the contrasts in the playing styles and/or personalities of the players (think McEnroe versus Bjorn Borg if you're old school, Federer versus Nadal if you're under 50). For that reason, this matchup has been under the radar. But the men have also met too few times on big occasions. And that may be changing.

The battle between players as similarly designed and perhaps even disposed as Soderling (ranked No. 4) and Berdych (No. 7) can be maddening as well as riveting. Much of what happens seems to be a matter of form-of-the-day. The similarities between these two are much more striking than the differences. Soderling, 26, is just a year older; Berdych at 6-foot-5 is just an inch taller, and their career records are almost identical: 289-162 for Soderling and 275-172 for Berdych. Both men have no fear of pulling the trigger and own excellent groundstrokes.

Neither of these guys has won a Grand Slam title, but each lost a Grand Slam final last year to Rafael Nadal. Their semifinal clash at Roland Garros last year was a glorious, brutal war (won 6-3 in the fifth by Soderling). I'd like to see more of the same.

Novak Djokovic leads Andy Murray (5-3): Much of what I wrote about the Soderling-Berdych rivalry could be repeated here, but as a pair, Djokovic and Murray are simply bigger names and (thus far) superior players. Their main problem is that Federer and Nadal have been just too big an obstacle.

Djokovic at this point is still a much better competitor, but my sense is that Murray is developing more slowly, and hasn't really hit his stride yet. If I'm right, these guys could have some spectacular battles -- if the usual suspects are otherwise occupied.

Caroline Wozniacki leads Petra Kvitova (3-1): Both of these women are 20, and born just months apart. And though Kvitova can't match Wozniacki's résumé (the Woz is, after all, No. 1 in the world), she's been coming on strong and has already blasted her way to No. 13 on the computer.

The battles between these two tend to be one-sided; they haven't played a three-setter yet, and while Kvitova trails in the H2H, she put up the most eyebrow-raising of the wins, a 6-2, 6-0 pasting of Wozniacki last year in the fourth round at Wimbledon.

Kvitova, who's got two inches on Wozniacki at 6-foot, has power and a willingness to attack, good tools to use against a rival who likes to outmaneuver and out-steady opponents.

Milos Raonic leads Richard Berankis (1-0): These two kids are the same age as Wozniacki and Kvitova, yet have met just once as pros and are nowhere near the top 10 in their own ranking structure (Raonic recently shot up to 37, while Berankis is 73). That tells you more about the difference between the slower-maturing men and the women than the contrasts between the ATP and WTA Tour ranking systems.

Both of these young guns have many matches to win before they start even thinking "rivalry." But the seeds have been sown. Berankis was a golden boy, earning recognition as the No. 1 junior in the world in 2007 after he won the Orange Bowl and U.S. Open junior titles. Raonic was relatively unknown, but seems to have developed and matured overnight. Their lone meeting thus far as main-tour pros was promising: Raonic won in the quarterfinals at San Jose (en route to his first ATP tour title), 6-4, 7-6 (2).

Berankis and Raonic will have a few other talented youngsters, including Grigor Dimitrov and Bernard Tomic, to contend with within their own generation. Which makes me wonder, is it too much to hope for a reprise of the McEnroe-Borg-Connors-Lendl era?

Andy Murray won his first-round match at the Barclays ATP World Tour Finals 6-2, 6-4 on Sunday. Big deal, right? A player like Murray, ranked No. 5 in the world and a multiple Grand Slam finalist, is supposed to cruise through the first-rounders.

But in this case, Murray's opponent was anything but a typical first-round stiff. He was Robin Soderling, who just replaced Murray at No. 4 and is a two-time French Open finalist and recent (as in last week) champion of the final Masters 1000 event of the year, the BNP Paribas Open.

And therein lies the problem -- or is it the glory? -- of the format used in the World Tour Finals. The ATP finals is an event restricted to the top eight players, divided into two equal groups, in which all of them play each rival in the group. Then, the top two finishers in each group move on to the knockout semifinals and final.

On paper, this is a can't-miss formula for a variety of reasons, not least of which is that the promoters can offer only blue-chip matchups and actually guarantee whom you will be watching on any given night, right up to the weekend. It's not like that in a typical single-elimination tournament, as any devastated Andy Roddick or Novak Djokovic fan can tell you when either of them (or insert your icon of choice) happens to be upset before the day for which his rabid fan has a ticket. In the television and Internet world, though, this consideration is less critical than ever before.

Trying to maximize the dramatic potential of an event has its perils. The round-robin format seeks to trump all other events with this "best against the best" formula. And although there's no doubt that the typical schedule at the World Tour Finals offers only premium matches -- all of them comparable to a Masters or Grand Slam event semi or final -- you have to wonder, how can they be? That's one of the big unresolved questions.

The downside of the eight-man, round-robin formula is that it can drain significance out of the preliminary encounters. At the end of the day, it's still just a tennis match, and somebody will win and somebody will lose. Similarly, if you made Roger Federer and Rafael Nadal meet 30 times a year, you would answer the fundamental question of who's better, but you would also lose some of the mystique of that rivalry.

The round-robin format also ensures that you can lose a match and still live to fight another day. It's a pretty good idea; it certainly works in the playoffs system used in Major League Baseball, National Basketball Association and National Hockey League. But the National Football League takes a different approach, and the NFL's win-or-go-home structure seems more in line with the gestalt in tennis.

I'm torn on this subject. It's like many other things in life: When everything is deemed meaningful, all things become equally meaningless. If you prefer a more pedestrian metaphor, eating chocolate cake three times a day is a pretty good way to make you think chocolate cake isn't so special after all.

One of the elements that make typical single-elimination events attractive is the mystery of the draw. Is it possible that Nicolas Mahut will beat John Isner? Will Robert Kendrick knock Nadal out of Wimbledon? Who's this Yen-Hsun Lu who just beat Roddick at Wimbledon?

The World Tour Finals lacks this critical element of unpredictability and therefore some measure of the drama and pacing of single-elimination tournaments. Nobody stands in the way of any other two players meeting, at least in the round-robin stage, which makes things somewhat mechanical. Mystery and unpredictability are pretty bit elements to surrender, but then nobody can ever say a World Tour Finals champion dodged and weaved his way to the title.

It's only fitting that the first singles match in the round-robin portion of the Barclay's ATP World Tour Finals in London on Sunday will feature Robin Soderling versus Andy Murray. You couldn't ask for a more symbolic kickoff in this, the year of the unknown.

We've had past year-end championships that sizzled with excitement and reverberated with significance -- how about the year 2000 in Lisbon, when Gustavo Kuerten had to beat Pete Sampras and Andre Agassi, both still in their prime, in back-to-back matches in order edge out Marat Safin for the year-end No. 1 ranking? Kuerten's top ranking was decided by the last official ATP tournament match of the year.

But I'm not sure we've had a field as competitive and unpredictable as the one now assembled in London. For one thing, I don't know that tour finals have ever boasted an aggregate 27 Grand Slam singles titles among the players, accounted for by four of the competitors -- Roger Federer, Rafael Nadal, Novak Djokovic and Andy Roddick. Given the enormous lead Federer has in that department over his rivals (Federer has 16 majors), you'd think he was the odds-on favorite to roll to victory, much like he did in four of the five years from 2003 to 2007.

But that's just not the case. Federer's game dropped a notch in 2010, and he's a clear-cut No. 2 behind Nadal. Loyalists will insist that you underestimate Federer at your peril on a fast indoor court, but the courts in Bercy last week were also slick and well-suited to Federer's slashing, piercing style. Yet he squandered five match points and experienced a crucial failure of nerve against Gael Monfils in the semifinals of the Paris Masters. And Monfils wasn't even consistent enough over the year to earn a berth in London.

For that matter, the defending champ also fell by the wayside on the road to London. Nikolay Davydekno, who's one of just three men to win the tour finals without a Grand Slam singles title in his career thus far (David Nalbandian, 2005; Alex Corretja, 1998), isn't in London this year. You might say that David Ferrer is the guy pinch-hitting for Davydenko. Ferrer appears to be the weakest of the eight players in the draw. Like Davydenko, he's struggled to turn in the quality W's. Ferrer is a combined 7-26 against the Big Three: Federer, Nadal and Djokovic (and winless in 10 matches with Federer).

But Nadal, despite finishing up a career year, doesn't appear to be in the best of shape, either. He maintained the form that helped him complete his career Grand Slam at the U.S. Open in the early fall, but he ran out of gas in Shanghai (losing to Jurgen Melzer in the third round) and then took a pass on Paris because of shoulder tendinitis. Does anyone else get the feeling that it will be hard for him to get back in the groove for the last tournament of the year?

The funny thing is, almost all the other contenders invite similar doubts or second-guessing. Tomas Berdych seems to have lost all the confidence he showed in the first half of the year; Soderling gained a measure of the same by winning Bercy. Djokovic may be cooling his jets, awaiting that all-important first-ever Davis Cup final for his nation, Serbia (the last major tennis event of the year). Murray is always a question mark and never more so than when playing at home in the UK. Roddick appears spent, but he's a salty veteran who won't blow what chances he gets.

All of which is why the Soderling-Murray opener is so appropriate. Even their head-to-head record isn't a predictor (2-2, all on hard courts but only one of them more recent than the winter of 2006).

It would take a brave soul to predict this one, but that seems to be true of the entire event this time around.

It seems that no matter what Robin Soderling does, he can't really escape his reputation as the spoiler. You know, the guy who rains on the parade. The guy with the pin in a world full of colorful balloons. The 26-year-old Swede even fits the stereotype of a bad dude. Does anyone in pro tennis, a sport full of guys with great hair and abs, which would make Mike Sorrentino re-evaluate "The Situation," look more like a repeat offender?

On Sunday, Soderling added to that spoiler reputation by snatching the BNP Paribas title from the hands of Gael Monfils. Both men were vying to go where neither had been before - the victory podium at a Masters 1000 (or better) event. Monfils had the Parisian home crowd, Soderling had the game. He imposed himself on "La Monf" in the manner any player must when his opponent is surfing on emotion and fan adulation. That is, he swarmed all over Monfils and kept the crowd out of it.

Soderling bludgeoned his way to the first set, 6-1, in the blink of an eye. By the time the French, including Monfils, were in recovery, Monfils was in desperate straits. He hung in there, but Soderling was heartless. He allowed Monfils a mere point in the second-set tiebreaker.

Some critics will say that Soderling won because this time he didn't have to beat any of the Big Three -- Roger Federer, Rafael Nadal or Novak Djokovic. You can add a fourth to that triumvirate -- Andy Murray, who has been playing some good tennis in recent weeks. But the difference between Soderling and many of his second-tier rivals, a group that includes Monfils, is that he's consistent and inclined to exploit his opportunities. The win over Monfils moved Soderling to No. 4 (replacing Murray) and can be interpreted as a shot fired across the bow of his main rivals for next week's ATP tour championships.

Soderling's record is worth examining in advance of the Barclays's ATP World Tour Finals, the last tournament of the year. Can he improve on last year's semifinal finish? (He lost a tough three-setter to the runner-up, Juan Martin del Potro. Remember him?) The numbers are not encouraging. Soderling is 1-5 versus Djokovic, 2-5 versus Nadal, 2-2 against Murray and -- get this -- 1-14 versus Federer.

Has anyone reaped more mileage out of a single win than Soderling's victory over Federer at the French Open?

On the other hand, Soderling won his most recent match with Djokovic (at last year's tour championships), he has swept his past two matches with Murray, and he's 2-2 against Nadal in their most recent meetings.

But that enormous deficit versus Federer sticks out like a sore thumb, and you know how it is in a round-robin of the kind they will play at the ATP season-ending finale. Soderling will be able to run, but he can't hide (not that a guy like him would want to).

Soderling is the first Swede to win one of the coveted ATP World Tour Masters 1000 trophies since Thomas Enqvist defeated Tim Henman in the 2000 Cincinnati final. Soderling is tough -- but also humble. As he said after winning in Paris: "I don't have a very good record in finals, and especially here in Paris [where Soderling lost two finals], but I think a final is that one match you really want to win. I'm really happy that I played well today, and now I'm here winning the title. When I won that last point, I just felt so happy and I felt so relieved. I really wanted to win this match so much."

This guy isn't just a spoiler -- he's much better than that. He can already pull rank(ing) on one of the big four (Murray), but that 6-26 record versus the elite should keep anyone from getting too carried away.

Call Juan Martin del Potro the X factor for the upcoming U.S. Open. He's the defending champ, and the guy who first demonstrated that if you play a sufficiently big, physical game, you can take down the Roger Federers and Rafael Nadals of this world (Robin Soderling and Tomas Berdych clearly were paying attention).

As few as two weeks ago, del Potro's prospects for playing at Flushing Meadows looked dim. But now, the news out of Argentina is that del Potro has recovered from the surgery on his right wrist, is hitting tennis balls and is on track to defend his title in late August.

That ought to give the top contenders the heebie-jeebies.

When del Potro manhandled Federer in the final of the U.S. Open last September, it seemed like an epoch-ending match. For the first time in a big match on a surface other than clay, Federer met a man who could play him on Federer's terms and still win. It was no one-off performance, either. In the two previous rounds, del Potro had knocked off Marin Cilic and Nadal.

And del Potro backed up that inspired U.S. Open triumph. In the ensuing weeks and months, he beat Federer again and put up a good win over hard-charging Soderling. His year-end head-to-heads looked like this:

Vs. Federer: 2-0 in the latter half of '09, despite trailing 0-6 after his loss to Federer at Roland Garros in the spring.

Vs. Nadal: 3-0 in '09 after Indian Wells, where his record slipped to 0-4.

Vs. Andy Murray: 1-5, with two losses to Murray on hard courts in the summer. Del Potro's crafted his lone win over Murray in Madrid (on clay) in the spring.

Vs. Novak Djokovic: 0-3 -- but no matches after Rome.

Vs. Andy Roddick: 2-0 in '09 and 3-0 in his career in two finals and one semi.

Del Potro took the big step into the first tier of players during the hard-court season. The only guy who still appeared to have del Potro's number by the end of last year was Murray. And Djokovic, who's showing signs of resurgence, is a big question mark.

Murray, a former U.S. Open finalist, looms as the main, proven stumbling block to del Potro when he returns -- if del Potro can muster the kind of tennis he was playing at this time last year.

That's a big "if." Del Potro hasn't hit a ball in competition since January, and he isn't the kind of player who is likely to benefit from the extra rest provided by his enforced absence. In fact, del Potro is just 21 and is blessed with Ironman propensities. Remember, he first appeared on the radar in 2008, when he won four straight events at the most demanding time of year -- in the summer, after Wimbledon.

That streak was a testament to his versatility, too. He won the first two titles on clay and shifted to his preferred hard courts without missing a beat. He won in Los Angeles and Washington and showed no signs of slowing down until Murray (him again!) finally quelled the del Potro insurgency in the quarterfinals of the U.S. Open.

A year later in New York, del Potro won the title.

The Argentine likes to go on rolls; it appears to build his confidence. His results in 2008 were impressive, but that win at Flushing Meadows last year didn't come out of the thin air, either. He won Washington and lost in the final of Cincinnati in the two events he played before the U.S. Open.

The big question is not whether del Potro will be able to play in the U.S. Open, but whether he'll get enough matches before the event to be at his best. I'm predicting that he'll play at least one event before he defends his title, and the news that he's hitting balls again supports the idea that he'd like to get a little match play under his belt before the last major of the year.

But consider this: The guy who beat del Potro in the final at Cincinnati last year was … you guessed it, Andy Murray.

So the X factor has an X factor of his own with which to contend.

Here's something interesting: Of the 64 matches that will constitute the first round of play at Wimbledon, 40 (by my count) will be between men who have never met before on a court with intent to hurt. That statistic, more than any other, demonstrates that despite all those familiar names and rivalries, your basic 128-draw Grand Slam event is part clash of the titans and part journey into the wild blue yonder.

What do you think the head-to-head record is between Dmitry Tursunov and Rainer Schuettler, two household names (in homes where tennis players or fans live, anyway)? Try 0-0. When the two veterans meet, it will be for the first time in an ATP Tour-level match.

How about Nicolas Almagro and Andreas Seppi? Believe it or not, 0-0. And Nicolas Mahut and John Isner? Actually, there is a record there: Mahut beat Isner in their only previous meeting, at Queens club in 2008.

Ah, the joys of bracketology.

I've considered previous history -- or I should say, the lack of history -- relevant ever since Pete Sampras admitted that he always found it tough to play guys for the first time. No matter how much scouting you've done, or how much better -- or worse -- your ranking is, you just don't know what your opponent brings to the game, like the unique way he moves, hits the ball and reacts to your own shots.

Only one first-round men's matchup features players who have met on more than four occasions, which is close to the baseline where the head-to-head becomes statistically significant. Those players are Marc Gicquel and Paul-Henri Mathieu, who have a five-match history, with Mathieu out in front by a nose, 3-2. None of those matches were on grass. I'd say that if you want to watch a potential barn burner in which only a crazy man would pick a favorite, this is it. Call your cable operator and demand that it broadcast the match, live.

Let's look at the top six seeds and see what comfort level they might feel going into their first-rounders:

No. 1: Roger Federer will be on familiar ground, having played Alejandro Falla four previous times. He won each encounter, and that includes two on grass. So far, Falla has won a set off Federer -- that's if you add up all the games Falla won in the course of the five sets they've played on grass (one match was at Wimbledon, the other at Halle a few weeks ago). Game, set, match, Federer.

No. 2: Rafael Nadal has played just one match against comeback kid Kei Nishikori. That was in 2008 at Queen's, when Nadal had to go three sets to beat young Kei. Advantage, Nadal.

No. 3: Novak Djokovic finds the shoe on the other foot, and he's got plenty of reason for concern. He's lost three of his four previous meetings with Olivier Rochus. But his lone win came on grass, via straight sets, at Halle last year. Still, the set scores were fairly close (7-6, 6-4), so Djokovic might have pregame jitters. Advantage, Rochus.

No. 4: Andy Murray meets Jan Hajek for the first time, but given how inconsistent Murray has been this year, and the pressure on him at Wimbledon, this match is no gimme. Advantage, Hajek.

No. 5: Andy Roddick will play Rajeev Ram for the first time, and his situation is oddly similar to Murray's. Many people would love to see Roddick win Wimbledon, and he himself burns for it. Self-inflicted pressure is better than outside pressure, but it will still make it a little harder to swing freely and play relaxed -- especially against a guy who plays with what can be called a similar American mentality. Still, advantage, Roddick.

No. 6: Robin Soderling meets Robby Ginepri, against whom he is 1-1. You have to assume that Soderling's firepower will be enough to overcome Ginepri's defense and counterpunching ability, and it will help Soderling that he's taken the measure of Ginepri's game before. Soderling knows the problems he's likely to present. Advantage, Soderling.

Me, I'm looking forward to the first clash between Mardy Fish and Bernard Tomic, which will pit the resurgent American, out to reverse his surprisingly disappointing history at Wimbledon, against a maturing prodigy who's been hailed as the savior of Australian tennis.

They have no previous history, and that just makes it all the better.