STANFORD, Calif. (AP) Second-seeded Dominika Cibulkova of Slovakia beat fifth-seeded Misaki Doi of Japan 7-5, 6-0 on Friday to reach the Bank of the West Classic semifinals.
Cibulkova, the 2013 champion, won the final 11 games after falling behind 2-5 in the first set.
She will face third-seeded Johanna Konta of Britain on Saturday at The Taube Family Tennis Center. Konta beat China's Zheng Saisai 6-2, 4-6, 6-3.
Alison Riske led fourth-seeded CoCo Vandeweghe 6-3, 1-0 in an all-American match when Vandeweghe retired because of an ankle injury. Vandeweghe was taken off the court in a wheelchair.
In the late match, top-seeded Venus Williams faced CiCi Bellis, the 17-year-old wild-card entry from nearby Atherton, California.