NEW YORK -- Andy Roddick's tennis career will close at the U.S. Open, the site of his biggest triumph.

The 2003 champion at Flushing Meadows and former No. 1-ranked player decided to walk away from the sport whenever his U.S. Open ends, making the surprise announcement at a news conference on Thursday, his 30th birthday.

"I'll make this short and sweet: I've decided that this is going to be my last tournament," said Roddick, wearing a black T-shirt and baseball cap with his clothing sponsor's logos.

"I just feel like it's time. I don't know that I'm healthy enough or committed enough to go another year," he said. "I've always wanted to, in a perfect world, finish at this event."

The 20th-seeded Roddick, who's earned $20,540,390 through Thursday in his career, is scheduled to play 19-year-old Bernard Tomic of Australia in the second round Friday night at Arthur Ashe Stadium.

"I think I wanted an opportunity to say goodbye to people, as well. I don't know how tomorrow's going to go, and I hope it goes well, and I'm sticking around," Roddick said.

He was, by turns, in reflective and joking moods while speaking to reporters about his decision.

"If I do run into some emotions tomorrow or in four days, I don't want people to think I'm a little unstable. Or more unstable," Roddick said with a chuckle. "So that's why I came to this decision."

His title in New York nine years ago was the last time an American man won a Grand Slam singles title, and Roddick spoke wistfully -- as he often has in the past -- about coming to the U.S. Open with his parents as a present when he turned 8.

He said he's "been thinking about (retirement) for a little bit," and knew for sure that the time now after his 6-3, 6-4, 6-4 first-round victory over 21-year-old American Rhyne Williams on Tuesday.

Andy Roddick, the last American man to win the U.S. Open, announced he would retire at the conclusion of the tournament. AP Photo/Frank Franklin II

"I've thought all year that I would know when I got to this tournament," he said, "and when I played the first round, I knew."

In addition to winning his U.S. Open trophy, Roddick also played in four other Grand Slam finals -- three at Wimbledon and one at the U.S. Open, losing to 17-time major champion Roger Federer each time. That included a 16-14 defeat in the fifth set at the All England Club in 2009, when Roddick was saluted by spectators who chanted his name at the end of the match.

Buoyed by a booming serve -- he used to hold the record of 155 mph -- and big forehand, Roddick is 610-212 (a .742 winning percentage) with 32 titles, including two this year at Atlanta and Eastbourne, England. He also helped the United States end a 12-year Davis Cup drought by winning the 2007 title.

"Look, he's been our best player for many, many years. Do we love to have a guy like that out there? Sure. Was it great that he's American? Sure," said U.S. Tennis Association CEO Gordon Smith. "We could use another dozen Andy Roddicks, and we're grateful for all he's meant to American tennis, to the Davis Cup, to the U.S. Open."

Roddick's announcement came one day after four-time major champion Kim Clijsters played the last singles match of her career, a second-round loss to Laura Robson at Flushing Meadows.

"I haven't done this before. I'm sure it'll be very emotional. I'm sure I'll still be nervous," Roddick said, looking ahead to facing Tomic. "I don't know."

He's been dealing with a series of injuries over the past few seasons, and in February dropped out of the top 20, then slid to No. 34 in March, his lowest ranking since 2001.

A hurt right hamstring forced Roddick to retire during his second-round match at the Australian Open in January, and he lost in the first round at the French Open and third round at Wimbledon.