Kiki Bertens, Petra Kvitova into St. Petersburg quarters

World No. 11 Petra Kvitova was defeated by Ashleigh Barty in last month's Australian Open. Photo by Chaz Niell/Getty Images

Top-seed Kiki Bertens stormed past Russia's Veronika Kudermetova, while third-seed Petra Kvitova edged Belgium's Alison Van Uytvanck, to reach the quarterfinals of the St. Petersburg Ladies Trophy in Russia on Thursday.

Bertens defeated Kudermetova inside of 57 minutes, serving six aces in a 6-1, 6-2 straight sets victory.

Kvitova won a closely contested opening set, ending when the Czech raced through a tiebreaker, before Van Uytvanck hit back in the second, breaking Kvitova's serve three times.

Two-time Grand Slam champion Kvitova edged the final set to win 7-6(1), 1-6, 6-2 and set up a quarterfinal match Russia's Ekaterina Alexandrova, who defeated Donna Vekic 6-1, 7-5.

World No. 11 Kvitova was knocked out in the quarterfinals of last month's Australian Open against Ashleigh Barty.

Elsewhere, Greece's Maria Sakkari advanced to the quarterfinals, where she will face top-seed Belinda Bencic, after powering past France's Alize Cornet in straight sets.