Novak Djokovic raises the bar yet again

To fully understand what has happened in the past 12-plus months of ATP tennis, and in the worlds of Novak Djokovic and Rafael Nadal, all you need to know is that the most compelling question raised after Sunday's Australian Open, while premature, is a reasonable one: Can Djokovic become the first man since Rod Laver to win a calendar-year Grand Slam?

Funny, but we were wondering the same thing at this time last year, except the subject was not Djokovic, but Rafael Nadal. It was a reasonable question then, because Nadal already had a career Slam on his résumé and had shattered Federer's image of invincibility.

It's even more relevant now, though Djokovic has yet to win the French Open. But having hammered Nadal on his beloved clay in Masters Series finals last year, and given his 70-6 final record, who'd rule it out? And -- irony of ironies -- Djokovic forced Nadal to feel the same emotions the Spanish No. 2 inflicted upon Federer when he began to beat him routinely on surfaces other than clay.

Could anyone have predicted that, even 18 months ago? Djokovic clearly has raised the bar beyond the seemingly unapproachable level Nadal had placed it until the 2011 season. Here are the main reasons:

Superior fitness: Up until the time Djokovic embraced a strict gluten-free diet and became more serious about his general fitness in all phases (preparation, maintenance, recovery), Nadal had a reputation as a man who would not finish second to anyone because of fatigue or loss of explosiveness.

Both Nadal and Djokovic were wobbly toward the end of their epic, 5-hour, 53-minute battle of Melbourne on Sunday, but Djokovic looked slightly more aggressive (which is partly a dividend of energy). Given that he had one less day of rest and had played a 4-hour, 50-minute semifinal against Andy Murray, it's safe to say we have a new beast in town.

Court position: Just as field position is critical to success in football, court position can be an enormous asset -- or liability -- in tennis. Djokovic's aggressive ground game and accuracy enables him to play from inside the baseline against quality opponents more than anyone with the possible exception of Roger Federer.

But Djokovic can do more damage than Federer with his basic tools during a typical point because he's better at redirecting the ball as part of his rally strategy, rather than as an attempt to hit a winner or approach shot, and also because of his superior backhand.

Service return: Nadal said it all in his postmatch presser: "Is something unbelievable how he returns, no? His return probably is one of the best of the history. That's my opinion, no? I never played against a player who's able to return like this. Almost every time."

Nadal was talking about that critical 4-2 game in the fifth set, when a hold would have given him a seemingly insurmountable lead of 5-2. Granted, Nadal missed that backhand pass that would have given him 40-15 instead of 30-all. But it was Djokovic's return in the ensuing points that earned him back the break that kept him alive.

The backhand: Djokovic has raised the two-handed backhand's status as a weapon much higher, even if the monster forehand is destined to remain the weapon of choice for most players.

Nadal dominates Federer partly because his lefty topspin to Federer's backhand is his go-to play. At best (on clay), it makes Federer hit his one-handed backhand from impossibly high. At worst, Nadal can use it to put Federer back on his heels, enabling Rafa to control the rally.

Not only can Nadal not do this to the Djokovic backhand, he courts disaster by trying. It certainly helps Djokovic that he's 6-foot-2, and thus has a big wheelhouse. But when you remember how often Nadal just treaded water with that slice backhand, the value of Djokovic's penetrating backhand jumps out at you.

Second-serve conversion: Wasn't it only 18 or so months ago when everyone was whispering that Djokovic was falling off the pace set by Nadal and Federer because of his unreliable serve? There were even matches in which he hit more double faults than aces.

Djokovic has rebuilt that serve, and his second serve recently has paid particularly high dividends. Against Nadal, there was scant difference between his winning percentage on first and second serve points (68 to 63 percent). Nadal, by contrast, was 66 to 45 percent. It's the key statistic of that titanic battle.

It can tell you a couple of things when your second-serve conversion percentage approaches that of your first-serve stats: You have a lousy first serve (you can throw that one out in this discussion); your second delivery is of extra-high quality in terms of spin, placement or power, or a combination of all three (that's relevant) and you are very good at keeping your opponent from taking control of rallies (also relevant).

Whether Djokovic wins the French Open and advances the discussion about a calendar-year Grand Slam, he's already taken the game to a place it hasn't been before. Didn't we just go through all this a year ago? Yes, but that was then and this is now.