Karolina Pliskova doubled up to reach the semi-finals of the Zhengzhou Open and Kristina Mladenovic claimed the scalp of Elina Svitolina on Friday.

The top seed's last 16 match with Polona Hercog was finely poised when rain forced its suspension on Thursday, with Pliskova trailing 5-2 in the second set having taken the first.

However, Pliskova rattled off five straight games to win 6-3 7-5 to progress to a quarter-final with Sofia Kenin, which she subsequently came through in three sets 6-4 4-6 6-1.

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

Pliskova will face Ajla Tomljanovic in the last four, the Australian another who had to play twice in the same day after 16 matches were postponed due to inclement weather 24 hours earlier.

Tomljanovic saw off Kiki Bertens in straight sets but had a more complicated passage through to the final four against Zheng Saisai.

After two hours and 35 minutes Tomljanovic won 6-1 6-7 (4-7) 6-4, moving a victory away from her fifth WTA final, having lost all of her previous four.

Kristina Mladenovic ousted second seed and US Open semi-finalist Svitolina, winning 6-4 4-6 6-3 to set up a showdown with Petra Martic, who ousted Aryna Sabalenka 7-5 5-7 6-4.