Giles Muller after defeating Andy Roddick on Tuesday

New York: For his 23rd birthday, Andy Roddick got a packed house at Arthur Ashe Stadium, a prime-time TV audience and a date with a six-foot-five left-hander from Luxembourg named Gilles Muller.

Unfortunately for Roddick, Muller showed up for his US Open debut with a booming serve that was far more effective than Roddick’s and a backhand that wasn’t nearly as flawed.

The result was a stunning upset that sent the 2003 US Open champion and tournament’s fourth seed packing in two hours six minutes, as Muller rolled to a 7-6 (7-4), 7-6 (10-8), 7-6 (7-1) win before a disbelieving crowd.

That said, it wasn’t as if Roddick played poorly. He committed just 15 unforced errors to 39 winners. The outcome was dictated far more by Muller’s sterling play ? smartly placed serves, crackling groundstrokes that tagged line after line, and the palpable zeal with which he attacked the ball.

Muller, 22, finished with 24 aces to Roddick’s 17,while hitting 65 winners and 33 unforced errors. “For me it was just unbelievable to come out here today,” Muller said during his on-court interview. “It was first time I played a night session in a Grand Slam. I told myself before the match, ‘Just go out there and enjoy it.’ And I did it every minute.”

Roddick’s defeat will no doubt trigger new rounds of criticism about the lack of variety in his game, which relies heavily on a big serve and booming forehand, and a new wave of soul-searching about the future of American tennis.

Said Roddick: “I don’t really remember a loss where I have felt this bad afterward. I love playing here. I probably had the best practice week I’ve ever had in lead-up. It just didn’t translate tonight. I just felt like the whole time I was trying to find something, as opposed to having it. ...I’m in a little bit of a shock right now, to be honest.”

Though he was won four titles this year, including Washington’s Legg Mason Classic, Roddick hasn’t posted the results insiders feel he’s capable of. He lost in the first week of the French Open and for the second year lost the Wimbledon final to world No. 1 Federer, who ran his record against the American to 10-1 with another victory in the final at Cincinnati two weeks ago.

The question swirling around Roddick on the eve of this year’s US Open was whether he would ever figure out how to beat Federer. American Express, one of the tournament’s major corporate backers, even built an ad campaign around thinly veiled allusions to Roddick’s inability to regain his No. 1 world ranking ? posing the question of whether Roddick would find his ‘mojo’.

But the humour of that campaign suddenly felt as flat as Roddick following his stunning defeat. “Muller was fabulous, but to say this is a shock is an understatement,” said John McEnroe.

LA TIMES-WASHINGTON POST NEWS SERVICE