It is a sign of the sceptical climate created by Lance Armstrong that when Novak Djokovic came off the court after confirming his place in the semi-finals, the questions were less about the smoothness of his backhand than how he could possibly maintain such a mind-boggling level of fitness.
Only two days previously, Djokovic had been pushed to the very edge in a 5hr 2min battle with Stan Wawrinka. Yet here he was, gambolling around the baseline like a faun and chasing down any number of apparently unreachable balls. Nobody actually asked him if he was popping any magic pills, but they might as well have done.
Faced with this potentially awkward situation, Djokovic responded like the dignified diplomat he has become.
"People who don't know tennis, who have never been in those kinds of situations would not truly understand what the player has to go through," he said.
"Not just when you prepare for a grand slam, but also during a grand slam. After five hours of a match, you need to really put a lot of time into recovery... I understand people have many different views and opinions, and I respect that. But I'm doing everything that is legal, that is correct, that is natural, and it's working well."
Djokovic's ability to regroup contrasted markedly with that of Gilles Simon, the Frenchman who was so wiped out by his 4hr 43min contest with Gael Monfils on Saturday that he might as well have brought an armchair on to the court for his meeting with Andy Murray yesterday.
But then Djokovic (right) was described by his defeated opponent yesterday, Tomas Berdych, as "the fittest guy on tour right now". And this was hardly the first time we had seen him bounce back like some human elastic band – exactly the same thing happened in Melbourne 12 months ago.
Then, he outlasted Murray over the course of nearly five hours on the Friday night, before taking down Rafael Nadal in the longest grand slam final ever played. His four-set, 151-minute canter against Berdych yesterday must have felt like a mere novella by comparison.
Djokovic's retrieving was at its bewildering best as he made Berdych earn each point. It was all too much for the Czech, who has never reached the semi-finals of this event. "This was quite a chance for me," he said, "but I didn't come up with my best game and that's what was decisive."
Berdych still contributed to an entertaining spectacle on Rod Laver Arena. He made a clumsy start, allowing Djokovic to romp through the first set, but he was able to snare the second with a barrage of huge serves and clumping forehands. After that, though, Djokovic found a rare rhythm as he swept to a 6-1 4-6 6-1 6-4 victory.
Djokovic claimed: "I felt good enough today to go another five hours." No one doubted him.
Meanwhile, David Ferrer, who will take injured Nadal's No 4 place in the rankings next week, pulled off the most remarkable escape of his career when he beat Nicolas Almagro 4-6 4-6 7-5 7-6 6-2 in their quarter-final.
Having lost the first two sets, Ferrer kept going behind in the third, during which Almagro served for the match on three occasions.
Ferrer broke back each time, took the set and went on to earn a semi-final meeting with Djokovic. (© Daily Telegraph, London)
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