Top seed Roger Federer continued his quest for a sixth U.S. Open championship with a second-round victory over German Bjorn Phau Thursday night.

But American Andy Roddick, who didn't even play Thursday, stole the headlines when he announced that he will retire following the season's final major tournament.

Roddick, who turned 30 on Thursday, captured his lone Grand Slam title at the 2003 U.S. Open and was the 2006 runner-up in New York. He will face Bernard Tomic in the second round Friday night.

"I just feel like it's time," Roddick said during a press conference. "I don't know that I'm healthy enough or committed enough to go another year. I've always wanted to, in a perfect world, finish at this event. I have a lot of family and friends here. I've thought all year that I would know when I got to this tournament. When I was playing my first round, I knew."

Federer cruised past Phau 6-2, 6-3, 6-2 under the bright lights at Arthur Ashe Stadium.

The 17-time Grand Slam king Federer, who captured his seventh Wimbledon title last month, is tied with Jimmy Connors and Pete Sampras with five U.S. Open titles. He is also going for his seventh championship this year.

In shocking news on the court, fifth seed Jo-Wilfried Tsonga lost to Martin Klizan, 6-4, 1-6, 6-1, 6-3, at Armstrong Stadium. The 52nd-ranked Slovak pulled off the stunner in 2 hours, 12 minutes by breaking a sluggish Tsonga a whopping seven times on Day 4.

The former Australian Open runner-up Tsonga is the second top-10 seed to fall this week, joining No. 10 Juan Monaco.

"Sometimes I'm in good shape, sometimes I'm not," Tsonga said at his post- match press conference.

The powerful Tsonga was a U.S. Open quarterfinalist last year and reached at least the quarters at this year's French Open and Wimbledon events, including a trip into the semis at the All England Club in July.

Czech Tomas Berdych, the No. 6 seed, handled Jurgen Zopp 6-1, 6-4, 6-2.

In other action involving top-20 seeds, sweet-swinging No. 11 Nicolas Almagro of Spain outlasted talented German Philipp Petzschner 6-3, 5-7, 5-7, 6-4, 6-4, No. 12 Croat Marin Cilic snuck past German Daniel Brands, 6-3, 6-2, 5-7, 4-6, 7-5, No. 15 Milos Raonic of Canada defeated Frenchman Paul-Henri Mathieu 7-5, 6-4, 7-6 (7-4), No. 16 Gilles Simon of France took down Jimmy Wang of Chinese Taipei 6-4, 4-6, 6-4, 6-4 and No. 17 Japanese Kei Nishikori spanked American Tim Smyczek 6-2, 6-2, 6-4 on the hardcourts at the USTA Billie Jean King National Tennis Center.

American Mardy Fish, seeded 23rd at the fortnight, started out slowly against former top-five Russian Nikolay Davydenko before overcoming a two-sets-to-love deficit en route to a 4-6, 6-7 (4-7), 6-2, 6-1, 6-2 victory at Ashe Stadium. Davydenko is a two-time U.S. Open semifinalist.

Fish needed 3 hours, 27 minutes to complete his comeback, which he did with the help of 16 aces and 10 double faults by Davydenko, who was broken eight times on Day 4.

American James Blake beat 24th-seeded Marcel Granollers of Spain 6-1, 6-4, 6-2, Spaniard Fernando Verdasco, the 25th seed, defeated fellow countryman Albert Ramos 7-6 (7-4), 5-7, 7-6 (7-5), 6-4 and 27th-seeded American Sam Querrey handled Ruben Ramirez Hidalgo of Spain 6-3, 6-4, 6-3.

Meanwhile, 30th-seeded left-hander Feliciano Lopez outlasted fellow Spaniard Pablo Andujar 6-4, 6-1, 6-7 (5-7), 3-6, 7-5 and promising 19-year-old American Jack Sock whipped Italian Flavio Cipolla 6-2, 6-2, 6-4. Lopez is rewarded with a match against Olympic gold medalist, Wimbledon runner-up and former U.S. Open finalist Andy Murray, while Sock will meet Almagro in the round of 32.

Frenchman Jeremy Chardy, the 32nd seed, breezed past Matthew Ebden of Australia 6-4, 6-2, 6-2.