Nadal, Henin heavy favorites heading into French

This is the time of year where Rafael Nadal and Justine Henin dominate on the tennis court. And with the French Open less than two weeks away, is there any reason to think both Nadal and Henin won't be winning their third straight title at Roland Garros? Can anyone challenge Nadal? Will American Serena Williams have as much success in Paris as she did earlier this year in Australia? ESPN tennis analyst Patrick McEnroe, stopped by to answer five burning questions before we head into the year's second slam.

Rafael Nadal has lost two sets in his last 17 matches on clay. What's it going to take to win a Grand Slam match against Nadal on a clay?

McEnroe: A miracle. That's a good place to start. Nadal is so confident right now and he's playing more aggressively on clay than he has in years past. It would take a Herculean-like performance. Nadal is not just strong physically, but mentally as well. To walk into a match against one of the greatest dirt-ballers to ever play and believe there's the slightest chance to take a set -- nevermind three -- against Nadal is not conceivable, not the way he's playing now. Look at what the Spaniard has done on clay since winning the French Open last year: 17 matches over a four-tournament span, including Davis Cup, and Nadal has lost a total of two sets. The bottom line is that a monumental effort is not enough. Someone would literally have to hit him off the court and run two marathons for three sets. And on clay, that's a feat unlikely to happen.

Which player not named Nadal has caught your attention on clay?

McEnroe: Let's be realistic. It's Nadal and everyone else. We're not going to discount Roger Federer, but he's visibly playing with less confidence than we've seen in a long time. Last year in Rome, these two played an epic final on clay, a match Nadal won in a fifth-set tiebreaker after Federer held two match points. And while Roger lost, that set the tone heading into Roland Garros. This year is a different story. The top-notch players who have a penchant for clay will believe they have a legitimate opportunity to compete with Federer, if not beat him.

The player who has caught my attention is Novak Djokovic. This is a kid who has made significant strides in 2007. He reached consecutive Masters Series finals in Indian Wells and Miami (he won the Sony Ericsson, defeating Nadal in the quarterfinals) and won a clay-court title in Estoril earlier this month. He was a quarterfinalist in Rome last week, losing to Nadal, but his game is well suited to all surfaces. Will this evolve into a French Open championship? Not now, but he is certainly someone to watch closely.

Which players pose as the greatest threat to knock two-time defending French Open champion Justine Henin off her throne?

McEnroe: The one candidate is the person who has played very little: Serena Williams. She's the X-factor. If she's fit and healthy, Williams has a viable shot at winning the French. We saw what she is capable of in Australia earlier this year. Very few, except Serena and her inner circle, thought she could pull it off, but that's what great champions do. She doesn't have to play a lot to make a statement. For Williams, it's about maintaining her fitness and avoiding injury. She won the French in 2002 and all signs indicate she will be a force this year. There aren't many players like her, those who can play so little but yet command so much respect.

Svetlana Kuznetsova is another contender, if she can get her head on straight. The Russian beat Henin in Berlin last week on clay, and her game is well-suited for dirt with a big forehand. She's strong, fit and moves well, and if she can hold it together mentally, Kuznetsova can compete with any women on tour.

The women's game, however, is in disarray. Amelie Mauresmo is coming off injuries and will be a question mark. Maria Sharapova probably won't play. Venus Williams doesn't have much of a chance. Martina Hingis has been a disaster lately, having yet to put together back-to-back wins on clay and Kim Clijsters is retired. There are very few players who will trouble Henin at the French.

Are you disappointed with the results of the U.S. men and women on clay?

McEnroe: Disappointed isn't the appropriate term; they just haven't played. Andy Roddick played one event in Rome and won't play again until the French. James Blake has competed in only two tournaments. Would I like to see them play more on clay? Yes, but I can understand it -- the rigors of the schedule have prevented them from competing. It's unfair to expect the top-two Americans to play Davis Cup and then head to Europe for three months. The goal is simple for the U.S. men: Reach the second week of the French. If they do, that's a win in and of itself. Their struggles have been well documented and as much as I would like to see them flourish, a fourth-round showing would be a step forward. The women's side is all about the aforementioned Serena Williams. We know she can play, we know she can win. She won't get many clay-court matches in before Roland Garros, and it's just a matter of going in healthy.

Is Roger Federer ready for the clay season to be over with?

McEnroe: Federer will he be happy when it's over, of course, because that signals the beginning of the grass-court season. But not so quickly; he's desperate to salvage a tumultuous clay season, one in which he split ties with coach Tony Roche. He wants to play well in Paris, obviously, and make a statement at the French. Federer won't be satisfied with a subpar result and, like any great player who's struggling, he wants to find an answer. He realizes what's at stake -- being dubbed the greatest player ever, and by winning the one slam that eludes him, that discussion only would intensify. It's not going to get any easier for him, though. Nadal is still going to get better and youngsters like Djokovic are improving and vastly moving up the ranks. Federer realizes time is slipping away and despite recent struggles, he'll show up in France ready and willing to win it all.

Let's not forget that Federer is the second-best clay-court player in the world right now. He hasn't played up to the standards we expect each and every time he takes the court, but aside from Nadal, he's the only player to reach the last two semifinals in France. This French Open is all about Nadal. Federer is unlikely to win, but don't expect him to go out without a fight.

Patrick McEnroe, the U.S. Davis Cup captain, provided analysis for ESPN.com during the tennis season.