American Jamie Hampton beat Stanford All-American Nicole Gibbs 7-5, 6-7(5), 6-3 on Thursday in the second round of the Bank of the West Classic,
The fourth-seeded Hampton is playing her first tournament as a seeded player.
Gibbs, playing in her fourth tournament as a pro, was cheered on by a group of the Rose Bowl champion Stanford football players, led by quarterback Kevin Hogan.
In other matches, third-seeded Dominica Cibulkova of Slovakia downed Switzerland's Stefanie Voegele 7-5, 7-6 (5), and No. 7 Urszula Radwanska beat Daniela Hantuchova 7-6(3), 7-6(3).
Cibulkova and Radwanska will meet Friday in the quarterfinal, while Hampton will play the winner of a late match between Madison Keys and Vera Dushevina.