An enforced vacation to rest his aching knees may have been just the tonic Rafael Nadal needed as he had a bounce in his step on Wednesday when he bludgeoned Richard Gasquet of France at the US Open.

Nadal, sporting a shorter haircut, a nice tan and looking relaxed after spending six weeks on his Mediterranean island home of Mallorca, was near perfect in a 6-2, 6-2, 6-3 first-round win and said his bout of tendinitis no longer weighed on his mind.

"I don't have pain, so I don't think," said athletic 23-year-old Nadal, who powered 27 winners past the Frenchman in the one-sided match.

Nadal, whose style of wearing down opponents under the weight of his groundstrokes has seemed to take a toll on him at end of long tennis seasons, is hoping this could be the year he completes a career grand slam by winning his first US Open.

"I am more fresh, yeah. Fresher than ever in this tournament," the Australian Open champion said with a smile, before adding, "I don't know if this kind of fresh is good."

The Spaniard temporarily shut down his season after failing to defend his title at the French Open.

Fed up with the pain he felt in both knees, he pulled out of Wimbledon and went home to rest and recover. He returned to business last month to prepare for the Open.

"When I was at home, I had few weeks outside of the world," the third seed said. "I was in Mallorca for one and a half months, but the first two weeks I was loose at home and having a lot of time of recover, doing nothing.

"It was a very positive thing for me. But I miss the competition, yes. I was for the last five years playing every week at hundred percent.

"I had one and a half months in the summer in Mallorca. It was a bad moment for holidays," he said about having to miss out on defending his Wimbledon crown.

"But the best moment for having holidays in Mallorca. So I enjoyed the summer in Mallorca."

Nadal, who relinquished his world number one status to Roger Federer during his absence, surprised himself by reaching the quarter-finals in Montreal and semi-finals in Cincinnati.

"I am very happy to be here another time, and I am enjoying much more practising with a better attitude than when I was playing in clay season with pain in the knees every day.

"I went on court without pressure," he said about returning to the sunny National Tennis Center where last year he reached the semi-finals before falling to Briton Andy Murray.

"Just thinking I feel I'm a very lucky guy to be here playing and enjoying this sport."

For Kim Clijsters, only when she beats the best will she know her comeback is truly on track.

The former world number one, back on tour after two years away and the birth of her first child, beat 14th seed Marion Bartoli of France 5-7, 6-1, 6-2 to reach the third round, her first grand slam since the 2007 Australian Open.

In her first two events back, the Belgian beat four top-20 players, including French Open champion Svetlana Kuznetsova of Russia.

But though her return has been impressive - reaching the quarter-finals on both occasions - the 26-year-old knows there are bigger hurdles to overcome.

"It was a nice feeling to have in Cincinnati and Toronto, knowing that I was capable of beating some of those top-ten players again," she said on Wednesday.

"So after those two tournaments, it was like, 'OK, I can beat those girls if I play well.'

"But I haven't played the big ones yet, Venus (Williams), Serena (Williams), (Maria) Sharapova, (Elena) Dementieva. I haven't played those girls yet. Hopefully I'll give myself a shot at doing that here."

Clijsters did play both world number one Dinara Safina and number five Jelena Jankovic, in Cincinnati and Toronto, respectively.

Both times she came off second best but she showed enough to suggest that with a few more matches under her belt, she may be able to add to the one grand slam title she has won, the 2005 US Open.

Before she can think of winning a second US Open title, though, Clijsters faces another Belgian in Kirsten Flipkens.

"Especially at the start of the tournament, you don't focus on eventually winning the tournament," she said.

Top seed and five-times champion Roger Federer withstood an inspired challenge from Simon Greul before defeating the pesky journeyman 6-3, 7-5, 7-5 in the second round on Wednesday.

The 28-year-old Greul squandered two set points in the second set and a 3-0 lead in the third, eventually succumbing to Federer's punishing groundstrokes.

"I just had to make him play more shots, be more tough," said Federer. "I had to raise my level today to win because that's what was required to get through."

On a chilly night at Arthur Ashe Stadium, few expected more than a light workout for the world number one. While the outcome was never in doubt, Federer had to sweat for the win.

The 28-year-old Swiss had the decisive third-set break against Greul in the 11th game to take a 6-5 lead.

Greul, ranked 65th in the world with no titles to his credit, wasted yet another break point on Federer's serve before the Swiss closed out the match with his eighth ace.

Federer's victory set up a third-round affair against 2001 champion Lleyton Hewitt, whom he has beaten 13 straight times.

"On any given day, a former world number one, a guy who's won majors, is very, very dangerous," said Federer.

"That's why I have to make sure I get into the match quickly, not give him the lead, because we know he's not going to go down without a fight.

Former world number one Amelie Mauresmo suffered her earliest ever loss at the US Open on Wednesday, beaten 6-4, 6-0 in the second round by Canadian Aleksandra Wozniak.

The 17th seed led 2-0 in the first set but then fell apart as the world number 39 cruised to victory to reach the third round in New York for the first time.

It is the first time Mauresmo has gone out of the US Open before the third round in 10 appearances.

Wozniak will now play 10th seed Flavia Pennetta after the Italian whitewashed Sania Mirza of India 6-0, 6-0.

Meanwhile, Mauresmo was unsure if she would return next year.

Holder Serena Williams brought an early curtain down on Wednesday's night programme by racing past Hungarian left-hander Melinda Czink 6-1, 6-1 in the second round.

In a break with tradition on Arthur Ashe Stadium, the women's match was scheduled after the men's contest in the evening session and the second-seeded Williams opted not to hang around for too long as she overwhelmed the 51st-ranked Czink in just 52 minutes under the lights.

The competitive fire in Williams seemed to ignite after a linesman called a foot fault on her when she served an apparent ace in the fourth game of the opening set.

Williams glowered in a slow burn at the linesman and then took her annoyance out on Czink, who sank under a barrage of 25 winners from the American, who will meet Maria Jose Martinez Sanchez of Spain in the third round.