NEW YORK—Everyone’s been curious about the condition of Rafael Nadal’s knees, so it made sense that his first Grand Slam opponent in three months would wonder as well.

Which might explain why Richard Gasquet tried a drop shot deep in the third set of his U. S. Open match against Nadal on Wednesday. Nadal made the long run necessary to get to the ball, and flipped it back over the net, winning the point.

A moment later, as if conspiring with Nadal to show everyone how fit the six-time major champion truly is these days, Gasquet offered up another drop shot.

Nadal got to that one, too.

Starting a bid to win the only Grand Slam title missing from his resume, Nadal encountered no apparent trouble from his much-scrutinized legs in a 6-2, 6-2, 6-3 victory over Gasquet at Flushing Meadows.

Gasquet, for one, was impressed.

“He can win the tournament,” said Gasquet, a 2007 Wimbledon semifinalist and former top-10 player. “Day after day, he will improve his level.

“For sure, he can win.”

Nadal’s matter-of-fact assessment: “I played well, no?”

Nadal didn’t wear any tape near his knees Wednesday, something he’s done in the past, much less the sort of bulky bandages Venus Williams showed up with near her left knee for a second-round match she won easily.

One could certainly make the case Nadal wasn’t facing the

toughest competition. Gasquet has been away from the tour, too, recently. He served a 2zmonth ban after testing positive for cocaine; Gasquet successfully appealed what would have been a far more severe punishment, saying the drug entered his system inadvertently when he kissed a woman at a nightclub.

Nadal’s absence was far more run-of-the-mill. He hadn’t played at a major tournament since May 31, when his 31- match French Open winning streak ended in the fourth round at Roland Garros. The Spaniard cited knee tendinitis in deciding not to defend his Wimbledon title, and the layoff was a big reason Nadal has dropped from No. 1 in the rankings to No. 3.

He ceded the top spot to Roger Federer, whose bid for a sixth consecutive U. S. Open championship — and third Grand Slam title in a row this year — progressed with a 6-3, 7-5, 7-5 victory over Simon Greul of Germany in front of a night-session record crowd of 24,206.

Next for Federer is a match-up against two-time major winner Lleyton Hewitt, who defeated Juan Ignacio Chela, 6-3, 6-3, 6-4. Federer has won 13 matches in a row against Hewitt, including in the 2004 U. S. Open final.

Williams, the 2000-01 champion in New York, had wide patches of white tape above and below her left knee, which began bothering her when she struggled through a first-round win Monday. Like Nadal, Williams looked hale Wednesday, and she easily dispatched Bethanie Mattek-Sands of the United States, 6-4, 6-2.

“She was moving like a cat,” Mattek-Sands said.

Serena Williams has joined her sister in the third round with a dominating victory.

The No. 2-seeded Williams was pretty close to perfect in beating 51st-ranked Melinda Czink of Hungary, 6-1, 6-1, in less than an hour.

Serena is seeking her fourth U. S. Open championship and 12th Grand Slam singles title overall. The American is trying to become the first woman to win consecutive titles at Flushing Meadows since Venus in 2000-01.

The sisters could play each other in the semifinals.

Kim Clijsters, who ended her retirement last month and is playing at the U. S. Open for the first time since winning the 2005 title, beat No. 14-seeded Marion Bartoli, 5-7, 6-1, 6-2.

Two fixtures on the men’s tour said goodbye to Grand Slam tennis with first-round exits: Marat Safin of Russia and Fabrice Santoro of France, who are retiring.

Safin lost to Jurgen Melzer of Austria, 1-6, 6-4, 6-3, 6-4; Santoro was beaten by No. 24 Juan Carlos Ferrero of Spain, 6-4, 6-3, 6-3.