ZHENGZHOU, China - Top seed Karolina Pliskova put in the hard yards on Friday to reach the semifinals at the Zhengzhou Open.

After finishing off Polona Hercog in a rain-delayed match, the World No. 2 downed American Sofia Kenin in a three-set match in the quarterfinals, 6-4, 4-6, 6-1. 

Read more: Pliskova powers past Hercog to reach Zhengzhou quarterfinals

Pliskova improved her head-to-head against the 20-year-old American to 4-0 with the victory, securing a second straight three-set win against her this year. The Czech previously recovered from 6-4, 2-0 down to win their most recent encounter, en route to winning the title in Rome in May.

"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 after the match.

"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."

On Friday, Pliskova shook off a second-set rally from Kenin to dominate the decider, having seen the No. 6 seed win three straight games from a break down in the second set to force a final set.  

The World No. 2 hammered 18 aces in the win overall, saving nine of 11 break points, and also saved all six break points she faced in the final set to become the first player through to the final four.

"On hard courts, she's always tough to beat. She also played a couple of matches here, and was fresh today because she didn't have to play a match. Last time, we played on clay in Rome and I won the tournament, so maybe it's going to be the same here," she joked.

"She's always fighting, and I had to play really until the last moment, so it paid off."

With one Rome rematch in the rearview mirror, Pliskova might get another one next: in the semifinals, she'll face the winner of the quarterfinal between Aussie Ajla Tomjlanovic and China's Zheng Saisai.

"I also played Tomljanovic in Rome, and in Brisbane on hard courts, so I know her game quite well, I could say," Pliskova said. "She's dangerous and beat Kiki Bertens, so she's playing well. I didn't see much of her tennis here, but it's the semifinals, so everyone is confident and playing their best tennis.

"With Saisai, we played a long time ago. She's doing more defending. We practiced the first day here, so I know her game a little bit. Chinese players always play well in China, so it's going to be difficult."