NEW YORK — This trick shot by Roger Federer was most definitely real.

He's even hit it before.

The five-time U.S. Open champion was up at the net when his first-round opponent, 96th-ranked Brian Dabul of Argentina, lofted a lob. Federer spun around to sprint toward the baseline. A couple of steps before reaching the wall behind the court at Arthur Ashe Stadium, and with his back to the net, Federer swatted the ball between his legs. The shot landed in a corner beside Dabul, who raised his eyebrows and shrugged.

"Only he can do that," Dabul said.

It was part of a remarkable 46-4 edge in winners for Federer during his 6-1, 6-4, 6-2 victory Monday night. It also was the highlight at Flushing Meadows on Day 1 of the tournament, when past U.S. Open champions Andy Roddick, Venus Williams and Kim Clijsters all advanced, as did surprise 2009 quarterfinalist Melanie Oudin, while 2001 champion Lleyton Hewitt lost in the first round at New York for the first time.

The sublime bit of shotmaking was nearly identical to a back-to-the-court, through-the-legs passing winner Federer hit against Novak Djokovic in the 2009 U.S. Open semifinals.

"This one was incredible again," Federer said. "I turned around and couldn't believe the shot landed in the corner."

Federer is, however, 16-0 in U.S. Open night matches, 11-0 in first-round matches at Flushing Meadows, and hoping to reach a seventh consecutive final in New York.

"I always loved coming here," Federer said. "Never had a bad U.S. Open."

Williams hasn't been too shabby at this tournament, either, with titles in 2000 and 2001, two runner-up finishes and nothing worse than a fourth-round loss. She looked pretty impressive Monday, becoming only the fifth woman with 200 Grand Slam match wins by beating Roberta Vinci of Italy 6-4, 6-1.

It was Williams' first match since a June 29 loss at Wimbledon; she missed time because of a sprained left kneecap, and landed awkwardly on that leg early in the second set.

"Thankfully," Williams said, "after that, she did most of the running."

Roddick turned 28 on Monday, and after beating Stephane Robert of France 6-3, 6-2, 6-2, the ninth-seeded American was asked what significance he attributes to his age. In typical Roddick fashion, he injected his reply with some humor.

"Obviously, I know I'm probably closer to the finish than I am to the start," he said. "But ... it's a number. I'm barely older than I was yesterday."

Well, that's true. He also, however, is 7 years older than he was when he won his lone Grand Slam title at the 2003 U.S. Open.

Clijsters won the U.S. Open each of the past two times she entered, in 2005 and 2009, and she stretched her winning streak in New York to 15 matches Monday despite a brief blip.

The No. 2-seeded Clijsters began her title defense with a 6-0, 7-5 victory over 104th-ranked Greta Arn of Hungary.