Djokovic has been struggling a little lately, at least compared to his dominance last year. He won in Australia, but then lost in the finals at the French to the #2 player, lost in the semifinals at Wimbledon to the (then) ranked 3 player, then lost at the Olympics to the 4 (world) player in the semifinals.
Not saying that rankings determine a player, but the trend has been that he has progressively lost to worst ranked players and been eliminated before the finals. And at Wimbledon and the Olympics, he pretty much got crushed by Federer and then Murray. I think the other players have made a bit of an adjustment, and now it'll be his turn to work harder to dominate again. He even barely made it to the finals at the US Open last year, he had to come back from 40-15 on Federer's match point.
I do think he's got the most potential, what with Federer's age and Nadal's knee, but he's going to have to up his game, or at least make it to the finals at the US Open, because he's just not quite playing at the same level as last year.
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Also, I don't know why, but I find myself not liking Djokovic. I respect his game and his amazing ability, but something about the guy annoys me. Maybe its the fact he looks like a dinosaur.
His racket of choice, however, I approve of. Head easily makes the best quality racket, in my opinion at least.