It was a struggle to sprint, and he scuffled against a foe who never has won a Grand Slam match, let alone a title. On a day when past champions Venus Williams, Justine Henin and Marat Safin advanced in straight sets, three-time French Open winner Nadal hardly looked ready to flourish at Flushing Meadows, where his career mark is worse than at any other major.

To improve on that, he'll need to recover quickly and perform better than he did before eventually earning a 7-5, 3-6, 6-4, 6-1 first-round victory over Australian wild-card entry Alun Jones, whose claim to fame is a bit part in the film "Wimbledon."

"I didn't run too much, no? I can't move too much," the No. 2-seeded Nadal said. "Difficult to play like this, especially here."

He felt a "sharp pain" in his left knee Sunday, toward the end of a practice session with Andy Murray in Arthur Ashe Stadium. The next day, Nadal didn't practice at all and figured he would have to withdraw from the year's last Grand Slam tournament — ruining a chance to meet No. 1 Roger Federer in a third consecutive major final.

Nadal had an MRI exam, though, that showed no significant damage, so he spent Monday and yesterday getting treatment on the knee from a doctor with the Italian tennis federation, Pier Francesco Parra, and a tour trainer. That helped, but he acknowledged that he might not have been on court Wednesday were this any other tournament.

Williams knows all about dealing with injuries — she missed the 2006 U.S. Open with a bum wrist and time this year with a bad knee — and she also knows a thing or two about winning major titles, six in all.

So she wasn't bothered by the six double-faults or the 20 total unforced errors she had to overcome in a 6-4, 6-2 second-round victory over Ioana Raluca Olaru of Romania.

"I missed a few shots that were easy, but ultimately, I mean, it's important to get to the next round. I always feel like my game will be there. I'm not stressed out on a few shots," said Williams, who won the 2000-01 Opens.

"I want to be the last one standing with a plate over my head. That's my goal every time."