BEIJING (AFP) - World number two Karolina Pliskova will play unseeded Ajla Tomljanovic in the semi-finals of the WTA Zhengzhou Open in China after winning two matches on the bounce on Friday (Sept 13).

Bad weather forced organisers to squeeze in second-round and quarter-final matches, meaning a tight turnaround for the top seed and her rivals.

But the Czech was unperturbed, first defeating Polona Hercog 6-3, 7-5, then beating Sofia Kenin of the United States 6-4, 4-6, 6-1 in the quarter-finals.

"To play two matches in a day is never easy, but in the first one I was lucky enough to not go to a third set, just finished quickly and saved some power for the next one," Pliskova, 27, said.

"I think I played good tennis in both matches. I was serving well today, a lot of aces, which always helps, and there's a lot of positive things for tomorrow."

Also into the last four in central China is Petra Martic from Croatia after she battled past Aryna Sabalenka of Belarus 7-5, 5-7, 6-4.

Martic will play unseeded Frenchwoman Kristina Mladenovic or the recent US Open semi-finalist Elina Svitolina of Ukraine.