STANFORD, Calif. (AP) New Zealand's Marina Erakovic stunned top-seeded and defending champion Victoria Azarenka of Belarus 4-6, 7-5, 6-2 at the Bank of the West Classic on Thursday to reach her second quarterfinal of the year.
The 121st-ranked Erakovic, a qualifier, recorded her first win over a top-20 opponent and has won 24 of her last 28 matches.
The fourth-ranked Azarenka reached the semifinals at Wimbledon in her last tournament.
Japan's Ayumui Morita recovered to beat qualifier Urszula Radwanska of Poland 4-6, 7-5, 6-1 and will next face Marion Bartoli.
American Serena Williams and Russia's Maria Kirilenko are scheduled to meet later Thursday, with the winner facing Maria Sharapova in the quarters.