There is no more fit player in men's tennis than Novak Djokovic, and that includes the indefatigable Rafa Nadal. The discrepancy between Djokovic's fitness and that of his closest rivals is easiest to see when Djokovic plays Andy Murray. For all the great skills Murray brings to the matches, Djokovic will always win the fitness battle -- see how he wore Murray down at this year's Australian Open after Murray's hot start.
One result of this fitness difference shows in how the two men are choosing to enter the year's second Grand Slam, The French Open. Djokovic is playing a lot of tennis, has won 19 matches in a row and just finished a tough three-setter against Thomaz Belluci to get to the quarterfinals in Rome. He'll play Kei Nishikori there. Andy Murray made a very different choice heading to Paris. He withdrew from the Rome Masters rather than play a scheduled third round match. Murray said, "My body is tired." He'll presumably be rested at Roland Garros, whereas Djokovic might be spent from his exertions. That is, if Novak Djokovic has ever felt spent. The French Open begins on May 24.
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