New York, NY

Former World No. 1 Andy Roddick surprised everyone when he announced on his 30th birthday that he will retire from professional tennis after this year's US Open.

"I'll make this short and sweet," Roddick said in a press conference. "I've decided that this is going to be my last tournament."

Roddick, who opened with a straight-sets win over countryman Rhyne Williams, will play 19-year-old Australian Bernard Tomic in the second round Friday evening at Arthur Ashe Stadium.

"It's been a process," Roddick added. "Certain parts throughout the year, I've thought about it, just with the way my body feels, with the way that I'm able to feel like I'm able to compete now, I don't know that it's good enough."

Roddick said he will focus on the sports and learning center that he will be opening next year in Austin, Texas, through his foundation.

"I'd like to be hands on with that and not see it periodically," he said. "I'd like to be kind of onsite every day. There's some other projects, kind of side projects, that I've been doing. Those excite me a lot right now."

The American won his lone Grand Slam title in 2003 at the US Open and became the youngest American to finish the season at No. 1 in the South African Airways ATP Rankings. Since turning pro in 2000, Roddick has won 610 matches and 32 titles. He became the 19th player in the Open Era to reach the 600 match wins plateau this year.

Roddick's announcement overshadowed Slovakian Martin Klizan's 6-4, 1-6, 6-1, 6-3 upset victory over No. 5 seed Jo-Wilfred Tsonga of France.

Klizan was more aggressive and determined throughout the match, hitting five aces compared to Tsonga's four, and had 32 winners to his opponent's 28. He will next face winner between No. 32 seed Jeremy Chardy and Matthew Ebden.

"I was coming to the match to play a very solid game," said Klizan. "I wanted to play really good tennis to play with the top star player. I played very, very well today. I was concentrating each point and I won; I'm very happy that I did."

American Mardy Fish rallied from a 0-2 set deficit for the second time in his career to defeat former World No. 3 and two-time US Open semi-finalist Nikolay Davydenko 4-6, 6-7(4), 6-2, 6-1, 6-2.

In other games, Spain's Feliciano Lopez edged countryman Pablo Andujar, 6-4, 6-1, 6-7(5), 3-6, 7-5, Japan's No. 17 seed Kei Nishikori enjoyed an easy 6-2, 6-2, 6-4 win over American Tim Smyczek and No. 11 seed Nicolas Almagro rallied to edge German Philipp Petzschner 6-3, 5-7, 5-7, 6-4, 6-4.

In women's play, fourth seed Serena Williams advanced to the third round with a 6-2, 6-4 win over Spain's Maria Jose Martinez Sanchez.

The three-time Open winner overcame 23 unforced errors to clinch her 60th career win at Flushing Meadows and a place in the next round against Russia's Ekaterina Makarova.

Second seed Agnieszka Radwanska joined Williams in the third round after beating Carla Suarez-Navarro, 4-6, 6-3, 6-0, while Maria Kirilenko aldo advanced with a 6-3, 6-2 victory over Greta Arn.