STANFORD, Calif. (AP) -- Varvara Lepchenko beat second-seeded Angieszka Radwanska 6-3, 3-6, 6-4 on Wednesday in the Bank of the West Classic to advance to the quarterfinals.
Lepchenko beat the fifth-ranked Radwanska for the first time in six meetings, edging a top-10 player for only the third time in 24 matches. Radwanska, the runner-up last year, became the highest seeded player to fall in the tournament.
Lepchenko will face Sachia Vickery, the American qualifier who beat Monica Puig 6-7 (4), 6-2, 6-1 to reach her first career WTA Tour quarterfinal. Vickery also won two straight in the main draw for the first time. Her only previous victory came at last year's U.S. Open in her WTA main draw debut.
Also, eighth-seeded Andrea Petkovic beat qualifier Naomi Osaka, 6-2, 6-2. Petkovic will next meet the winner of Thursday night's match between Venus Williams and Victoria Azarenka.