LOS ANGELES: Russian Vera Zvonareva outlasted Yanina Wickmayer 7-6 (7/5), 4-6, 6-4 in the third round of the 700,000 dollar WTA LA Tennis Championship.

The second seeded Zvonareva, who lost in last year's final, will next face Flavia Pennetta at The Home Depot Center facility in south central Los Angeles.

The 10th-seeded Pennetta registered an upset by beating fifth-seeded Russian Nadia Petrova 6-3, 6-3.

Another upset on day four of the hardcourt tournament came when 13th-seeded Aussie Samantha Stosur ousted former world number one Ana Ivanovic 6-3, 6-2. Serbia's Ivanovic was seeded sixth and is a former French Open champ.

In other action, eighth-seeded Agnieszka Radwanska, of Poland, breezed past Russian Anna Chakvetadze 6-3, 6-2.