LOS ANGELES • Petra Kvitova had not lost to a fellow Czech in 24 matches over nearly six years.
That all changed on Wednesday at the Charleston Open when the 28-year-old lost 6-1, 1-6, 3-6 in the second round to Kristyna Pliskova.
World No. 10 Kvitova, a two-time Wimbledon winner, won a lopsided opening set before her 77th-ranked opponent took control.
Pliskova's aggression saw her cruise through the second set and the 26-year-old went on to break her opponent twice in the decider to book a third-round spot in the WTA's first clay-court event of the season.
"My serve was horrible in the first set, so I had to focus on my serve and the rest of the game was better then as well," said Pliskova, who won just 13 of 34 points on her serve in the first set.
"I'm really happy, it's my second top 10 win this year, but also it's against Petra."
Pliskova blasted six aces and broke Kvitova's serve six times in the two-hour match.
Kvitova also committed 44 unforced errors, with most of them coming in the final two sets.
She broke Pliskova's serve five times but made nine double faults. It is the first time she has lost to a compatriot since 2012.
Pliskova, identical twin of world No. 6 Karolina, will next face 16th seed Elena Vesnina, who eased past Taylor Townsend 6-4, 6-1.
In another upset on Wednesday, British sixth seed Johanna Konta was beaten 6-3, 6-4 by Hungarian qualifier Fanny Stollar, who blasted 28 winners to defeat the world No. 22 in 1hr 20min.
The 19-year-old, ranked 219th in the world, will next face 12th seed Kiki Bertens, who beat Serbia's Aleksandra Krunic 6-4 6-2.
In other matches, Naomi Osaka of Japan outlasted Germany's Laura Siegemund 6-3, 7-6 (10-8).
REUTERS, AGENCE FRANCE-PRESSE