ZHENGZHOU, China — Top-seeded Karolina Pliskova won two hard-fought matches to reach the Zhengzhou Open semifinals on Friday.

Pliskova had to wait 1 1/2 days to complete her second round match as she beat Polona Hercog 6-3, 7-5 but not before saving five set points in the second set. Pliskova was trailing 5-2 in the second set when play was suspended on Wednesday. Rain prevented play on Thursday and the organizers had to reschedule matches for Friday.

Pliskova returned to court later Friday to beat sixth-seeded American Sofia Kenin 6-4, 4-6, 6-1 in the quarterfinals.

"To play two matches in a day, it's 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 said.

"I was serving well today, a lot of aces, which always helps, and there's a lot of positive things for tomorrow."

Pliskova faces Ajla Tomljanovic in Saturday's semifinals after the unseeded Australian defeated local favourite Saisai Zheng 6-1, 6-7 (4), 6-4.

Seventh-seeded Petra Martic of Croatia upset fourth-seeded Aryna Sabalenka of Belarus 7-5, 5-7, 6-4. Martic will meet Kristina Mladenovic in the semifinals after the Frenchwoman defeated second-seeded Elina Svitolina 6-4, 4-6, 6-3 in a quarterfinal that finished well beyond midnight local time.

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