NEW YORK (AP):

Chants of "Let's go, Andy!" rang out between points during the last service game of his career and again before the start of what would wind up as the last return game.

Always a fan favourite at the US Open and the 2003 champion, Andy Roddick headed into retirement with a 6-7 (1), 7-6 (4), 6-2, 6-4 loss to Juan Martin del Potro of Argentina in the fourth round at Flushing Meadows yesterday.

It was an emotional farewell for Roddick, who sat in his changeover chair, covering his face with a white towel, after sailing a running forehand long on the last point. He choked up during an on-court speech at Arthur Ashe Stadium, telling the crowd, "Oh, wow. For the first time in my career, I'm not sure what to say.

"Since I was a kid, I've been coming to this tournament. I felt lucky just to sit where all of you are sitting today, to watch this game, to see the champions that have come and gone," Roddick told the fans. "I've loved every minute of it."

The American surprisingly announced last Thursday, his 30th birthday, that the US Open would be his final tournament. That impromptu news conference came a day before Roddick's second-round match and he wound up winning that one, and a third-rounder, too, riding a wave of support in the stands.

But those two opponents were ranked 43rd and 59th and the seventh-seeded del Potro, the 2009 US Open champion, provided a far more daunting challenge - especially once he lifted his energy level and got his big, flat forehand cranked up.

Roddick made a brief appearance at No. 1 following his only Grand Slam trophy - and the most recent for an American man - nine years ago. He appeared in four other major finals, losing to Roger Federer each time and wound up with 32 tournament titles overall.

hope for future

"It's been a road of a lot of ups, a lot of downs, a lot of great moments. I've appreciated your support along the way," Roddick said. "I know I certainly haven't made it easy for you at times, but I really do appreciate it and love you guys with all my heart. Hopefully, I'll come back to this place someday and see all of you again."

Del Potro joined the fans in standing to applaud. He moved on to a quarter-final against defending champion Novak Djokovic, who advanced when his opponent, No. 18 Stanislas Wawrinka, stopped because of illness and fatigue while trailing 6-4, 6-1, 3-1.

Djokovic's Serbian Davis Cup teammate, No. 8 Janko Tipsarevic, finished his rain-interrupted 6-3, 7-6 (5), 6-2 victory over No. 19 Philipp Kohlschreiber of Germany, and gets No. 4 David Ferrer of Spain in the quarter-finals.

And, a point away from going down two sets, Andy Murray rallied to take all the momentum from Marin Cilic and reach the semi-finals.

The Olympic gold medallist won 3-6, 7-6 (4), 6-2, 6-0 last night. He trailed 5-1 in the second set before breaking twice to come all the way back.

Four-time major champion Maria Sharapova won her quarter-final yesterday, coming from behind after a rain delay for the second consecutive match and defeating 2007 Wimbledon runner-up Marion Bartoli 3-6, 6-3, 6-4.

Sharapova was down 4-0 on Tuesday when play was stopped. But she wound up improving to 12-0 in three-set matches this year.

"It's a great statistic. It shows that I enjoy the battle no matter what the score is," Sharapova said. "The third set, it's the last set out there and there's no reason why you shouldn't put everything out there."