Karolina Pliskova, the top seed at the Western & Southern Open, was stunned by Russian world No.41 Veronika Kudermetova in the second round on Sunday in New York.

Kudermetova clawed her way back from 1-4 down in the opening set to defeat the Czech 7-5 6-4 and book a place in the third round.

“I just tried to fight every point, to stay focused on every game and I’m really happy about this win,” said an elated Kudermetova, after scoring just the second top-five win of her career.

Over on Grandstand court, second seed and reigning Australian Open champion Sofia Kenin followed Pliskova out of the tournament, succumbing to French world No.60 Alize Cornet 6-1 7-6 (9-7) after a dramatic second set.

Kenin was trailing 1-6 2-5 before she saved two match points, rallied back from a double-break down and inched ahead 6-5. In a gripping tiebreak, Cornet saved two set points and finally wrapped up the upset on her fourth match point.

“You know I’m a fighter, I’m always fighting, so it’s not new. My God, I can barely breathe,” Cornet said after the win.

Meanwhile, 2017 US Open champion Sloane Stephens suffered her seventh defeat in eight matches this season, falling 6-3 7-6 (7-4) in her first-round clash with Frenchwoman Caroline Garcia.

Australian Open quarter-finalist Ons Jabeur survived a tough duel with 17-year-old Canadian Leylah Fernandez, coming through 0-6 6-4 6-3 in one hour and 55 minutes.

Jabeur will face No.7 seed and defending champion Madison Keys in the next round.