Fifth-seeded Misaki Doi and No. 7 seed Alize Cornet each needed three sets on Monday night to advance to the second round of the Bank of the West Classic.
Doi, who advanced to the fourth round of Wimbledon earlier this month, cruised past Xinyun Han 6-0 in a 24-minute first set but fell 2-6 in the second. Doi started the third set by winning three straight games en route to 6-2.
Cornet, the world's No. 51st-ranked player, beat Jennifer Brady 3-6, 6-4, 6-4 in a match lasting 2 hours, 43 minutes and will face Saisai Zheng.
Nicole Gibbs topped fellow Stanford standout Carol Zhao 6-2, 4-6, 6-3 in the first evening match. Gibbs, who won NCAA singles titles in 2012 and 2013, advances to play No. 4 seed CoCo Vandeweghe on Thursday. Gibbs is partnered with Zhao in the 16-team doubles field.
Top-seeded Venus Williams, a recent Wimbledon semifinalist and a four-time Olympic gold medalist, plays her first match of the women-only tournament on Wednesday night.