(Reuters) - Kristyna Pliskova pulled off the biggest win of her career but it was bad news for twin sister Karolina who was on the receiving end of a 6-2 3-6 7-6(7) defeat at the Birmingham grasscourt event on Wednesday.
The world number 112 fired down 24 aces as she beat world number three Karolina in their first meeting in a WTA event.
It was her first win against a top-five ranked player and she will go on to play fellow Czech Barbora Strycova in the quarter-finals.
The twins set up the second-round clash after Karolina accepted a wildcard and defeated Mihaela Buzarnescu on Monday while Kristyna came through three rounds of qualifying before beating Viktoriya Tomova.
Kristyna, two minutes older than her sister, broke early in contest and raced ahead 5-1 before closing out the opening set with an ace.
Former U.S. Open finalist Karolina, who lost the last clash between the pair at the Eastbourne qualifiers six years ago, responded strongly to drag the match into a decider.
World number 112 Kristyna surged 4-1 ahead in the third set but Karolina fought back to force a tiebreak. A third double fault by Karolina at 7-7 gave her twin match point and Kristyna held her nerve to seal a memorable victory.
Kristyna is seeking a second career title since her triumph at the Tashkent Open in 2016.
(Reporting by Shrivathsa Sridhar in Bengaluru, editing by Ed Osmond)