A U.S. Open Series event
Wednesday
At The Taube Family Tennis Center
Stanford, Calif.
Purse: $710,000 (Premier)
Surface: Hard-Outdoor
Singles
Second Round
Sachia Vickery, United States, def. Monica Puig, Puerto Rico, 6-7 (4), 6-2, 6-1.
Varvara Lepchenko, United States, def. Agnieszka Radwanska (2), Poland, 6-3, 3-6, 6-4.
Andrea Petkovic (8), Germany, def. Naomi Osaka, Japan, 6-2, 6-2.
Serena Williams (1), United States, def. Karolina Pliskova, Czech Republic, 7-5, 6-2.
Doubles
First Round
Daniela Hantuchova, Slovakia, and Arantxa Parra Santonja, Spain, def. Daria Gavrilova, Russia, and Xu Yi-Fan, China, 3-6, 7-6 (2), 10-8.
Paula Kania, Poland, and Katarina Siniakova, Czech Republic, def. Chan Hao-ching, Taiwan, and Andrea Petkovic (4), Germany, 6-2, 3-6, 10-8.
Quarterfinals
Garbine Muguruza and Carla Suarez Navarro (3), Spain, def. Caroline Garcia, France, and Zhang Shuai, China, 6-0, 7-5.