New York ? Playing on a taped-up knee so painful he almost pulled out of the U.S. Open, Rafael Nadal was hardly at his imposing best Wednesday. 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 his rival, No. 1 Roger Federer, won easily, 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, Nadal will 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.”

Federer had no difficulty at all Wednesday night, when he was dressed for a formal affair as he bids to become the first man since the 1920s to claim four consecutive U.S. championships. He strode out for his 6-1, 6-4, 6-4 victory over Paul Capdeville in black, head-to-toe: bandanna, wrist band, shirt, shorts, socks and shoes. The shorts even had satin stripes down the sides.

Now Federer faces a much taller task: His third-round opponent is John Isner, the 6-foot-9 American who only a few months ago was playing college tennis for Georgia. With fans barking for their favorite Bulldog, Isner followed up his first-round upset of No. 26 Jarkko Nieminen by beating Rik de Voest of South Africa 6-3, 6-3, 7-6 (4).

Like Federer, other past U.S. Open champions in action won in straight sets: Venus and Serena Williams, Justine Henin and Marat Safin.