NEW YORK - Roger Federer and Serena Williams will begin the defence of their US Open titles at Flushing Meadows today, while Kim Clijsters returns to grand-slam tennis for the first time in two years.

World No 1 Federer, chasing a modern-day record sixth straight title at Flushing Meadows, plays American wild card Devin Britton in the first round in his first grand-slam event since the birth of his twins last month.

The Swiss, bidding to add the US Open to the French Open and Wimbledon titles he won earlier this year, is hoping to equal the mark set by American Bill Tilden in the 1920s.

Moreover, Federer can extend his record of grand-slam wins to 16 by winning in New York. It is a far cry from 12 months ago when he arrived in New York without having won one of the first three grand slams for the first time since 2002.

"I'm just more relaxed this time," he said. "I've already won slams this year. That takes away pressure from having to do well here, like the feeling I had last year, not having won a slam last year, trying to get the first one.

"This year is different. I feel like I'm playing great. That gives me obviously a lot of confidence and relaxes my mind."

Fifth seed and 2003 winner Andy Roddick, the runner-up to Federer at Wimbledon, opens his campaign against German Bjorn Phau.

Women's champion Serena Williams, seeded second, plays fellow American Alexa Glatch in the first round. Serena's sister, third seed Venus Williams, plays the first night match against Russian Vera Dushevina. - Reuters