Karolina Pliskova battles through to semifinals in Tianjin

Top seed Karolina Pliskova took another step towards the end-of-season WTA Finals as she defeated Britain's Katie Boulter at the Tianjin Open.

The world No. 6 from the Czech Republic came back from a set down and then a break down in the decider to see off Boulter 5-7, 6-0, 6-3.

She will play Timea Bacsinszky in the semifinals after the Swiss upset No. 4 seed Aryna Sabalenka in two tight sets.

Bacsinszky, who is returning from a long term leg injury, upset the odds to record a 7-6 (2), 7-6 (5) win which ended Belarussian Sabalenka's chances of competing in the season-ending finals in Singapore.

Second seed Caroline Garcia made her way into the semifinals after Croatian opponent Petra Martic retired hurt. France's Garcia led 6-2, 1-0 when Martic was forced to pull out.

Garcia will play Su-Wei Hsieh in the semifinals. The No. 5 seed progressed ahead of Elise Mertens who retired with the score 6-2, 4-0.