Karolina Pliskova takes a selfie with fans after her win over Petra Kvitova at the WTA Finals in Singapore on Thursday. Photo: VCG

Czech Karolina Pliskova stormed into the semifinals Thursday after a convincing straight-set victory against compatriot Petra Kvitova, sending the former Wimbledon champion crashing out of the WTA Finals in Singapore.

Pliskova became the first player into the final four after a 6-3, 6-4 triumph in 83 minutes. Kvitova needed to win in straight sets to keep her campaign alive but struggled throughout to complete a disappointing first WTA Finals appearance since 2015.

The result puts pressure on reigning champion Caroline Wozniacki, who needs to defeat unbeaten Elina Svitolina in straight sets to keep her title defence alive.

Former world No.1 Pliskova booked her spot in the semifinals for the second straight year.

"I can't be happier right now," she said after the match.

"Everything has been working well for me this week. I don't want to think of the trophy ... I'll just do what I can to recover."

Kvitova's slump in Singapore continued, serving three double faults to be broken in the second game of the match and her confidence spiralled.

It was one-way traffic with Pliskova dominating off the baseline and picking off Kvitova's timid shots to rattle off the opening four games.

On the brink of elimination, Kvitova showed some fight by attacking Pliskova's powerful serve and breaking in the fifth game.

But Pliskova regrouped to close it out in 41 minutes and eliminate Kvitova, who had 15 unforced errors in the first set.

With the pressure off, Kvitova went for her forehands and it paid off as she began hitting the lines.

The 28-year-old broke in the second game and stormed to a 4-2 lead as it appeared a seventh straight match at the WTA Finals would go the distance.

But Pliskova rediscovered her rhythm to win four straight games and defeat Kvitova for the first time after three straight losses.