China's Sun Tiantian ousted Samantha Stosur of Australia to enter the second round of the US Open, while teammate Li Na became an early casualty, after losing to Lindsay Davenport.

Sun Tiantian, who joined Li Ting to win the women's double's title in the Athens Olympics, upended the Aussie in straight sets 6-3, 7-6 for her opening victory.

China's number two Li Na, however, failed to conquer world top player Davenport, losing the match 6-4, 6-4.