PARIS - Hopping in place in a hallway leading to the court, Rafael Nadal was drenched with sweat before he smacked a ball in his French Open quarterfinal.
A study in perpetual motion, Nadal actually got a bit of a breather Wednesday, when Novak Djokovic of Serbia-Montenegro quit with a back injury after losing the first two sets. That put defending champion Nadal into the semifinals at Roland Garros with what goes into the books as his 58th consecutive victory on clay, extending his record.
"The fact that today's match was, I wouldn't say comfortable, but low-intensity, is going to help Rafael," said Nadal's coach and uncle, Toni. "It's great to compensate for the long matches he's had."
That's hardly good news for Nadal's next opponent, Ivan Ljubicic, who beat Julien Benneteau of France 6-2, 6-2, 6-3 to reach his first semifinal in 27 trips to Grand Slam tournaments.
With No. 2 Nadal facing No. 4 Ljubicic, and No. 1 Roger Federer playing No. 3 David Nalbandian on Friday, it's the first time since 1985 that the men seeded 1-4 at the French Open all made the semifinals.
"I don't think there's any doubt that (Nadal) is a big favorite. Of the four of us left, he is definitely the favored one," said Ljubicic, who hasn't faced a seeded player in the tournament. "Just by reaching the semifinals, I did something incredible. There's absolutely going to be zero pressure for me."
The French Open is generally regarded as the most grueling tournament on tour, and this year's edition apparently was as tough as any.
Djokovic's retirement was the eighth of 2006, the most among men at Roland Garros in the modern era.
Like the other majors, it requires players to string together seven victories over two weeks to earn the title. Unlike the others, it's played on clay, which tends to extend points and matches, making stamina and will as important as superb strokes.
As well-stocked as the 20-year-old Nadal is with all three of those components, even he was grateful to get off the court after fewer than two hours Wednesday: He logged more than eight hours over his previous two matches.
"For those of us more used to playing on clay, maybe we resist a little more, but sometimes we have a tough time, too. We feel the pain, too," he said.
Djokovic also retired at last year's French Open, in the second round.