Call it "rivalry interrupted." When Nadal was rocked out of Wimbledon by the hot hand of Lukas Rosol, and then promptly pulled the plug on the rest of the year because of recurring tendinitis in his knees, he was denied the chance to re-establish his superiority over world No. 1 Novak Djokovic.
Curiously, Nadal went through something very similar in 2009, when he lost at Roland Garros for the first time in his career and then was unable to defend his Wimbledon title. That was back when his main and most storied rival was Roger Federer. Nadal returned to the tour in the fall of 2009, but he didn't full recapture his form until early 2010.
In 2012, Nadal chose not to make a comparable attempt to salvage his season at the risk of playing before he was fully recovered. That was probably a wise decision, but it remains to be seen how quickly he can whip himself into tournament-ready shape after the longest-by far-layoff of his career.
Best Case Scenario: The "conservative" approach Nadal chose, partly to avoid surgery but also to give his knees a good, long rest and rehab period, could pay off for him-especially because the off-season for his rivals is so short.
Worst Case Scenario: Nadal learns that there's no real substitute for being in the flow of tournament play, and crashes out with some early-and perhaps ugly-losses. I don't even want to think about what may happen if his knees start acting up after a few weeks of the kind of stress you can only get from match play.
Australian Open Outlook: I wouldn't expect a great deal out of Nadal in Oz, because his history suggests that he needs time to dial in his A-game and confidence. He hasn't lost before the quarterfinals in Melbourne since 2005, however, so he should feel comfortable on the surface right out of the gate.