Russian Alisa Kleybanova scored a upset victory over top seeded Jelena Jankovic of Serbia 7-5, 6-2 in the second round of the Mercury Insurance Open at San Diego.

Jankovic started with 4-0 in the first set and had three set points at 5-3 but couldn't convert the opportunity. The Russian bounced back strongly and clinched the opening set 7-5. She continued to roll with the momentum and closed the second set 6-2.

Another former world no 1 Dinara Safina lost to fourth seeded Agnieszka Radwanska of Poland 6-1, 6-3.

This year French Open finalist Samantha Stosur advanced to the quarterfinals with a 6-4, 6-4 win over American Melanie Oudin.

“I felt like at the start I wasn’t timing the ball as well as I wanted to,” Stosur said. “But as the match went on, I felt like I played better and better. I dictated and thought I served well. Overall, I was very happy.”

“Sam is pretty much an extremely tough opponent for me, especially because of her kick serve and her serve,” Oudin said. “It’s really, really tough to break her. It puts a lot of pressure on my serve because I know that I have to hold.”

In other match of the day, seventh seed Shahar Peer of Israel prevailed 7-5, 6-4 against Yaroslava Shvedova of Kazakhistan.