SINGAPORE — Karolina Pliskova won the first set to eliminate Petra Kvitova, and then won the second set to advance to the semifinals at the WTA Finals.
Pliskova, who advanced from her group for the second straight year, beat Kvitova 6-3, 6-4 on Thursday to improve her record to 2-1 at the season-ending tournament.
It was Pliskova's first victory over Kvitova in their fourth meeting.
"I knew I lost my other matches to her. I knew this time I had a chance because I was playing pretty well in my other two matches here," Pliskova said on court after the match. "Everything is working well for me this week so I'm just happy."
In the other group match, Elina Svitolina stayed unbeaten and advanced to the semifinals by beating defending champion Caroline Wozniacki 5-7, 7-5, 6-3.
Kvitova jumped out to a 3-0 lead in the second set, but Pliskova then won six of the next seven games. Kvitova finished the group with three straight losses.
"I still had a lot of positive thoughts in the match to fight and turn it around, even (if it) didn't happen," Kvitova said. "I still need to be fine because I still have the Fed Cup final (against the United States) coming up."
Kvitova, who is from the Czech Republic, rarely loses to players from her country. Since the 2012 Madrid tournament, the two-time Wimbledon champion has won 27 of 29 matches against Czech opponents.
Her only other loss to a Czech player in that time period was to Pliskova's twin sister, Kristyna, at this year's tournament in Charleston, South Carolina.
Svitolina only needed to win one set in the late match to advance, but she had to wait for it.
Wozniacki nearly pulled off the straight-set victory, which would have given her a place in the semifinals instead. But she squandered two game points in the final game of the second set and then sent a backhand long on a fifth-set point for Svitolina.
"It was an amazing match and a tough fight because Caroline always brings the best out of you," Svitolina said on court. "You have to push your limits against her."
Wozniacki, who finished with a 1-2 record, felt she was second best on the day.
"I played well in big parts of the match and I had chances in the second set to close it out but it wasn't to be," Wozniacki said. "I gave it my all and she just played better than me today."
Svitolina believes reaching the semifinals should quiet recent social media comments suggesting she'd lost too much weight.
"It was not easy with all the things going on social media and opinions with my physique," Svitolina said. "This really shows that I'm getting mentally tough and that's what I've been working on really hard. "I've learned there's thousands of opinions, millions of opinions and I need to just do my job."