New York - World number ones Roger Federer and Victoria Azarenka, Olympic men's champion Andy Murray and defending women's champion Samantha Stosur are among the tennis stars playing on Monday at the US Open.
Three-time US Open champion Kim Clijsters, playing in the final event of her career, and Russian beauty Maria Sharapova, who completed a career Grand Slam by winning the French Open in June, are also in action on day one.
The year's final Grand Slam tournament begins on the Flushing Meadows hardcourts with 56 matches, with the men's first round spread across the first three days and the women's opening round set to be completed in two days.
Top seed Federer has the last night match at Arthur Ashe Stadium against American Donald Young while Stosur, seeded seventh, begins her title defence in the first match on Arthur Ashe Stadium when she faces Croatian Petra Martic.
British third seed Andy Murray, fresh off an Olympic gold medal after beating Federer in the London final at Wimbledon, will play American Alex Bogomolov Jr in the first men's match on Ashe.
Azarenka is fourth on Louis Armstrong Stadium against Russia's Alexandra Panova while Sharapova and Clijsters claim the other spots at Arthur Ashe.
Clijsters, seeded 23rd, opens the night session Monday against American Victoria Duval while third-seeded Sharapova plays Melinda Czink in the last match of the afternoon session.
Czech fifth seed Petra Kvitova, fresh off a victory in Saturday's New Haven WTA final, will meet Slovenia's Polona Hercog on the Grandstand court on Monday afternoon.
China's Li Na, the ninth seed, plays the first match on court 17 against Britain's Heather Watson.