Flushing Meadows, NY (My Sportsbook) - Five-time defending champion Roger Federer gained a third-round matchup with Australian Lleyton Hewitt at the U.S. Open, while former world No. 1 superstar Rafael Nadal was an easy opening-round winner Wednesday in the final Grand Slam event of the year.

The world No. 1 Federer topped Germany's Simon Greul, 6-3, 7-5, 7-5.

It was a reversal of sorts at the night session as the men played first at Arthur Ashe Stadium for the first time at the tournament rather than having the women take the court.

"I knew it was going to be a battle and the level was really high," said Federer. "It feels great to be back and feels great to have a win again."

It was the super Swiss' 36th straight victory at the U.S. Open and moved him into a third-round encounter with Hewitt, as the 31st-seeded Australian posted a 6-3, 6-3, 6-4 victory over Argentine Juan Ignacio Chela.

Federer has owned Hewitt, beating him 13 straight times. That includes a straight-set triumph at the final at the 2004 U.S. Open.

"We have had some incredible battles over the years," said Federer. "He's a great man and I hope we can play a great match."

Although Federer won in straight sets, Greul had his chances, but couldn't convert despite having two sets points in the second set. Federer saved them and then broke for a 6-5 lead before using a dominating serve to take a commanding lead.

Greul won the first three games of the third set, but Federer came charging back and broke for a 6-5 edge. He ended the match with an ace.

A third-seeded Nadal blew past talented Frenchman Richard Gasquet 6-2, 6-2, 6-3 at the Billie Jean King USTA National Tennis Center.

Gasquet returned to ATP play here after serving a drug-related suspension this summer.

The 23-year-old Nadal is a six-time major champion, including this year's Aussie Open title, but has yet to reach a U.S. Open final. He was a semifinal loser at the hands of Scottish star Any Murray here a year ago.

Nadal's second-round opponent will be dangerous German Nicolas Kiefer.

Sixth seed Juan Martin del Potro downed Juan Monaco, 6-3, 6-3, 6-1, in an all- Argentine matchup. Ninth seed Gilles Simon of France defeated Spaniard Daniel Gimeno-Traver, 6-4, 7-6 (7-3), 6-3.

Thirteenth-seeded Gael Monfils advanced to the second round with a 6-1, 6-4, 6-3 pasting of fellow Frenchman Jeremy Chardy on Day 3.

Former U.S. Open champ Marat Safin came up an opening-round loser in his final trip here, as the former top-ranked Russian star gave way to tough Austrian lefthander Jurgen Melzer 1-6, 6-4, 6-3, 6-4.

Safin, who captured one of his two major titles here in New York nine years ago by blasting the legendary Pete Sampras in the final, had already announced that this would be his final season on the ATP World Tour.

"It could have been a better ending, but it's still okay," said Safin. "I'm looking forward to afterwards in my career, so I have no regrets, and I don't care about losses anymore."

Melzer will next face del Potro.

Spaniard David Ferrer, the 18th seed, beat fellow countryman Alberto Martin, 7-5, 5-7, 6-3, 6-3.

Former U.S. Open runner-up Juan Carlos Ferrero took care of 36-year-old Frenchman Fabrice Santoro, 6-4, 6-3, 6-3, in round one. The 24th-seeded former world No. 1 Ferrero was the U.S. Open runner-up in 2003. Santoro, like Safin, is expected to retire by year's end.

In other first-round action involving seeds, No. 32 Spaniard Nicolas Almagro got past Belgian Steve Darcis 6-2, 6-4, 2-6, 7-6 (10-8).

Additional opening-round wins came for Germans Andreas Beck and Kiefer, Austrian Daniel Koellerer, Brazilian Thomaz Bellucci, Argentine Jose Acasuso, Uruguay's Pablo Cuevas, German Philipp Petzschner and American Robby Ginepri, who came from behind to best Romanian veteran Andrei Pavel 5-7, 6-2, 6-4, 6-0. Ginepri was a semifinalist here four years ago.

The second round continues Thursday with fifth-seeded American Andy Roddick in the feature match, playing at Arthur Ashe Stadium at night against Frenchman Marc Gicquel. Roddick lost to Federer at the epic Wimbledon final this year and won the U.S. Open in 2003 before finishing as the runner-up in 2006.

Fourth-seeded Serbian Novak Djokovic, the 2008 Australian Open champion, plays Aussie Carsten Ball. Eighth-seeded Russian Nikolay Davydenko faces Czech Jan Hernych.

Two other high-profile Americans are in action. James Blake, the 21st seed, takes on Belgian Olivier Rochus, while 22nd seed Sam Querrey battles fellow countryman Kevin Kim.