STANFORD, California (AP) — Top-seeded Agnieszka Radwanska beat Francesca Schiavone 6-4, 6-3 on Wednesday to reach the quarterfinals of the Bank of the West Classic.

The No.4-ranked Pole beat Schiavone for the fourth straight time, having lost their first four matches.

Fifth-seeded Sorana Cirstea beat American Coco Vandeweghe 6-3, 6-3 and No. 6 Varvara Lepchenko advanced with a 6-4, 6-4 victory over Austria's Tamira Paszek.

The 32nd-ranked Cirstea, Romania's second-ranked player, reached the semifinals last year. She'll meet unseeded Olga Govortsova in the quarterfinal. Govortsova upset second-seeded Samantha Stosur.

"I'm happy to be back," Cirstea said. "I played well here last year and have many good memories. It's a good start to what is to come."

The 40th-ranked Lepchenko reached her second quarterfinal of the season and will face Radwanska.