NEW YORK (AFP) - Reigning US Open champions Roger Federer and Serena Williams will begin defending their titles on Monday as an opening-day match list released Saturday also had Venus Williams and Andy Roddick at night. The year's final Grand Slam tournament commences on the Flushing Meadows hardcourts Monday with former world number one Kim Clijsters of Belgium facing Ukraine's Viktoriya Kutuzova in the first match at Arthur Ashe Stadium. Clijsters is making her first US Open appearance since winning the 2005 women's title, her only Grand Slam crown. She returned to the court earlier this month after a layoff of more than two years to start a family. Federer, who has won the past five US Open men's titles and has not lost at the US Open since the fourth round in 2003, begins his quest for six in a row against 18-year-old American Devin Britton in the second match at Ashe. "Doesn't matter who you play, where you play. If you think the guy is not going to make a game that's absurd," Federer said. "That's how tennis is. You have to be very careful. I have to make sure I put in a good performance." Federer recalled being shocked at 17 when he faced Andre Agassi in his hometown of Basel, so he can relate to Britton's situation. "You try to enjoy it, put in a good fight," Federer said. "Best-of-five-set match is maybe something Britton has never played before, but a good thing in tennis is you always have a chance." US fifth seed Andy Roddick's advice for Britton was to find ways to help cope with a signature moment on the big stage. "There's nothing like going out on that court and playing," Roddick said. "I would him to be sure to have a look around when he walks out on the court, take it all in before you go start warmup so you don't catch yourself looking around too much when you start." Serena Williams, who won her 11th career Slam title last month at Wimbledon, begins her quest for a fourth US Open title in the following match against American Alexa Glatch. The main court's night session starts with US third seed Venus Williams meeting Russia's Vera Dushevina followed by men's fifth seed Roddick facing Germany's Bjorn Phau. US Open officials have said they plan to stage a women's match after a men's match at some point during the Flushing Meadows fortnight. Men usually play the later matches in part because they are best-of-five compared to the best-of-three on the women's side.