INDIAN WELLS, Calif. (AP) -- Top-ranked Novak Djokovic defeated Kevin Anderson 6-2, 6-3 to reach the fourth round of the BNP Paribas Open on Monday, improving his match record to 12-1 this year.
In the day's biggest upset, No. 6 seed Sam Stosur lost to 30th-seeded Nadia Petrova 6-1, 6-7 (6), 7-6 (5) in a rematch of their three-set U.S. Open marathon last year. That was the longest women's match since the tiebreaker was introduced, with Stosur winning on her way to claiming the title.
Francesca Schiavone became the eighth player to withdraw because of a viral illness sweeping the Coachella Valley.
Big-serving John Isner defeated Juan Monaco 7-5, 7-5, leading a contingent of Americans in action as the tournament began its second week. Mardy Fish, Andy Roddick and Ryan Harrison played third-round matches later.
Defending women's champion Caroline Wozniacki was set to play a night match against Sofia Arvidsson of Sweden.