CHARLESTON, S.C. — Kristyna Pliskova rallied from a set down to knock out two-time Wimbledon champion Petra Kvitova at the WTA's Volvo Car Open on Wednesday.

Kvitova of the Czech Republic won six of the first seven games to take the opening set before countrywoman Pliskova came back for a 1-6, 6-1, 6-3 victory to advance to the round of 16 in the WTA's first clay-court event of the season.

Kvitova had won 24 straight matches against Czech players before Pliskova's victory.

Pliskova, ranked 77th, is the identical twin of top-10 player Karolina Pliskova, a former world No. 1.

Kristyna got some sisterly advice from Karolina on facing the two-time Grand Slam winner.

"It really helped because she knows her better than me," said Kristyna Pliskova.

The change, Pliskova said, came when she began to get her serve in the final two sets.

"First set was horrible and that's the biggest difference," she said.

No. 6 seed Johanna Konta of Australia also lost, falling in straight sets to Hungary's Fanny Stollar 6-3, 6-4.

Stollar said she was able to dictate points most of the match against Konta. "I think I pushed my game to her and I stayed really aggressive," said Stollar, who entered the week ranked 219th in singles.

Madison Keys, the U.S. Open runner up last year, needed three sets to take down Lara Arruabarrena of Spain 6-1, 3-6, 6-3. Keys, at No. 7, is the highest seeded American left in the tournament.

No. 5 seed Julia Georges of Germany topped American Kristie Ahn 2-6, 6-4, 7-6 (1), No. 8 Anastasija Sevastova of Latvia defeated Caroline Dolehide of the United States in three sets, 7-5, 6-7 (5), 6-1, No. 9 seed Australian Ashleigh Barty ousted Tatjana Maria 4-6, 6-3, 6-2 and No. 10 seed Naomi Osaka of Japan defeated Laura Siegemund of Germany 6-3, 7-6 (8).

Other seeded winners were No. 12 Kiki Bertens of the Netherlands, No. 13 Irina-Camelia Begu of Romania and No. 14 Alize Cornet of France.

No. 11 seed Daria Gavrilova of Australia lost in three sets to Italy's Camila Giorgi.