NEW YORK – Andre Agassi sat alone, staring blankly at an Arthur Ashe Stadium doorway, the silence punctured by the rustling leaves on nearby trees.

Soon, he’d walk through that exit, his U.S. Open done with a 6-3, 2-6, 7-5, 3-6, 6-3 loss Thursday to top-ranked Roger Federer in a quarterfinal, suspended by rain early in the fourth set the night before and wrapped up in the worst of swirling winds.

In those idle moments on a lobby bench, there was plenty for the 34-year-old Agassi to contemplate. The immediate past: How did that match slip away? And the future: How much longer do I want to put in the work it takes to compete?

“My game plan is to play until I can’t do it,” Agassi said. “I certainly want to be able to assess my level of play, and at some point my level of play will dictate my decisions. But as of right now, I’m trying to win tournaments, and I believe that with that focus, I can still do that.”

The eight-time major champion certainly gave Federer all he could handle, stretching a man 11 years his junior to the limit. It wasn’t gorgeous tennis, but it couldn’t possibly be with gusts approaching 40 mph.

Picked up by the chair umpire’s microphone, the wind provided a thunderous bass-line to a soundtrack that included the ruffling of shirts and empty cups clattering in the stands. Towels flew off changeover chairs, and a let was called when a silver hot dog wrapper slid by Federer’s feet during a rally.

With a point here and there making the difference, Federer was superb, breaking Agassi in the next-to-last game and displaying the win-the-big-ones instinct he’s developed. The Wimbledon and Australian Open champion has won 10 straight tournament finals; he’s 15-0 against top 10 players since November.

Federer’s first U.S. Open semifinal will be against another player never this far at Flushing Meadows: No. 5 Tim Henman, who beat No. 22 Dominik Hrbaty 6-1, 7-5, 5-7, 6-2. On the other side of the draw, 2001 Open champion Lleyton Hewitt overwhelmed Tommy Haas 6-2, 6-2, 6-2 to set up a semifinal against defending champ Andy Roddick or No. 28 Joachim Johansson, who played at night.

Hewitt was remarkably efficient, making 10 unforced errors, but Haas might have come up with the shot of the tournament. At 5-1 in the third set, Haas sprinted from the net to the baseline and, his back to the court, smacked a shot between his legs that zoomed over the net. When Hewitt volleyed, Haas deposited a passing shot, then reared back on his heels, raised his arms, looked to the sky and swung an uppercut, celebrating as if he won the match.

One game later, though, Hewitt did win, making the Open’s semifinals for the fourth time in five years. He hardly seemed harassed by the wind.

“You had to be patient and mentally tough out there and not let it bother you,” Hewitt said. “I didn’t really let it worry me at all.”

Agassi was trying to become the oldest Open champion since 1970. Instead, Federer moves on in pursuit of his third Grand Slam title of the season, something done just twice in the last 30 years: by Mats Wilander in 1988, and Jimmy Connors in 1974.

“He’s a little bit older than me, but he’s not 50 or 60,” Federer said with a smile. “He can still run and play, he can win tournaments, and he can beat the best.”

Agassi was shocked in the first round at the French Open, and he pulled out of Wimbledon with a bum hip. But he played well in U.S. Open tuneups, beating Roddick and Hewitt en route to the Cincinnati Masters title.

His compact swing and quick footwork might have given him the edge Thursday if there hadn’t been a strong breeze. This was much more.

Serve tosses were tough; were they pitchers, both players would have been called for a balk or two. The net bulged like a boat’s sail, and balls danced randomly. On one point, Federer wound up to hit a backhand, then had to switch midswing and flubbed a forehand when the ball darted 2 feet over.

“Anything more than this, there would have to be some serious consideration into postponing matches,” said Agassi, who finished 34 winners to Federer’s 54. “Hitting the ball in the dead center of the court was a great shot.”

Federer tilted and nearly fell over before one serve, and he double-faulted four times in one fourth-set game, which should make the public-park set feel good.

“I had to kind of toss it behind me so it would come forward, and hope that it would land in the right spot,” Federer said. “That’s how extreme it is.”

Those doubles helped Agassi get four break points, and he converted the last with a forehand that found the net cord and plopped over. Agassi seized the opening, and evened the match at two sets apiece by closing a 15-stroke point with a forehand winner, prodding a standing ovation from fans thinking: The ol’ guy’s still got it.

“At that point,” Federer acknowledged, “I was worried.”

But Agassi, who said last week he wouldn’t retire after the Open, got broken to 5-3 in the fifth. In that game, Federer hit a backhand lob that rolled through the wind and landed right on the baseline, “perfect,” Agassi called it.

Federer then served it out, slicing backhands that Agassi overhit. And just like that, quick as a blink, it was over.

“If I’m out there forcing the best players in the world to play their best tennis, if I’m out there with other players not looking forward to playing against me-that’s everything it’s always been,” Agassi said.

“So I’m going to keep going as long as I feel I have the realistic hope of putting together great matches and finding a way to win.”