(Reuters) - Top seed Karolina Pliskova overcame a slow start to put away Britain's Katie Boulter 5-7 6-0 6-3 in the Tianjin Open quarter-finals on Friday, improving her chances of qualifying for the WTA Finals in Singapore.
Pliskova, currently eighth in the Race to Singapore standings, is battling for one of the three available spots in the season-ending tournament starting on Oct. 21.
World number 101 Boulter, facing a top-10 player for the first time, took her Czech opponent by surprise with two breaks of serve to clinch the opening set.
Pliskova is known for her powerful serve but it was her return game which came to the rescue as she converted nine break points to move past Boulter into the semi-finals.
"(In the second set,) I started with a quick break, which always helps a little bit, and I improved my serve," world number six Pliskova said.
"I played more aggressive, I thought, and she didn't have time much to play her game, and that was the difference."
Earlier in the day, fourth seed Aryna Sabalenka suffered a shock 7-6(2) 7-6(5) defeat by Swiss Timea Bacsinszky, which ended the Belarusian's chances of participating in the WTA Finals.
Having recently returned to action from a serious leg injury, Bacsinszky deployed the full range of her groundstrokes to reach her first WTA semi-final since the French Open last year. The 29-year-old will face Pliskova for a place in the final.
France's Caroline Garcia also booked a spot in the last four after her sixth-seeded opponent Petra Martic retired, trailing 6-2 1-0.
(Reporting by Nivedita Balu in Bengaluru; Editing by Toby Davis)