Gilles Muller has been a pro for five years, but he didn't fully grasp the pressure that players such as Roger Federer and Andy Roddick confront routinely until Thursday. That's when Muller's meteoric start to this year's U.S. Open came crashing down with a 6-1, 6-1, 6-4 defeat at the hands of American Robby Ginepri.

Just two days earlier, the gangly left-hander from Luxembourg had become the story of the tournament thus far, defeating Roddick, the 2003 champion and this year's fourth seed, in the first round. Muller pulled off the stunning upset in straight sets by manhandling Roddick's vaunted serve and blistering the lines with groundstrokes that rarely missed.

But it was a shadow of that player who showed up for Thursday's second-round match on Louis Armstrong Court.

The 6-foot-5 Muller's serve was nowhere to be found; he managed just five aces, compared to the 24 he notched against Roddick. And whatever homing device his groundstrokes once had was also missing, as he sprayed nearly twice as many unforced errors (39) as winners (20).

Muller, 22, took pains to credit Ginepri's sharp play afterward. "I can't only say that I played bad; he made me play bad, also," Muller said. But he also faulted himself for being unprepared for the fallout from his first-round triumph.

"I think it was too much for me," Muller said. "I mean, I played great against Andy. Today, I played worse but, I mean, it wasn't the tennis. I think it was something in the head."

Muller didn't get to sleep until 2:30 a.m. after the Roddick match. He woke up the next day at 8 a.m. to play doubles (with his partner, Ginepri). He was bombarded with phone calls. And was floored by all the fans screaming his name and waving flags of his tiny country as the roamed the grounds at the National Tennis Center.

"I wasn't ready for that," Muller said. "I didn't know that I can have so much impact on the people. I have to realize it and deal with it now."

Ginepri, 22, has negotiated his own painful learning curve as a pro. An accomplished junior, he pouted his way through his early setbacks as a pro, sulking when he lost matches he thought he should have won. Only after his ranking slipped below 100 did he recommit himself to the game. A sports psychologist also helped, he said.

"Definitely I'm a lot smarter upstairs now," said Ginepri, who is 16-3 in his past 19 matches. "I don't make any stupid unforced errors like I used to. I don't check out in the middle of points. I'm concentrating."

Navratilova Advances

Martina Navratilova took her first step toward a 10th Grand Slam mixed-doubles title as she and India's Leander Paes advanced to the second round with a 6-3, 6-2 victory over Tatiana Golovin and Fabrice Santoro of France.

Luxembourg's Gilles Muller, above, who stunned fourth-seeded Andy Roddick in the first round, is wiped out by Robby Ginepri, 6-1, 6-1, 6-4.