TOKYO, Japan - No.4 seed Karolina Pliskova had to dig deep once again at the Toray Pan Pacific Open in Tokyo, this time needing three sets to see off Donna Vekic and reach the final.

After saving two match points against American qualifier Alison Riske in the last round, and coming back from a set down against Daria Gavrilova earlier in the tournament, Pliskova had to go the distance once again, needing 2 hours and five minutes to defeat Vekic 6-2, 4-6, 6-3.

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“It was another long one today!” Pliskova said after the match. “I feel like I’m improving in every match, but the opponents are always more tough. That’s normal in semifinals - there’s no easy opponents.

“I think Donna was playing well and she’s beaten a lot of tough players this tournament. I was expecting a tough one. For a while it was looking like it maybe could be under two hours, but not really.”

It was a nearly-untouchable first set of tennis from the former World No.1, as Pliskova shut down everything Vekic threw her way. The Croat was going for the early strike, but Pliskova wasn’t giving any opportunities as she dominated the rallies. She broke Vekic to start, and then immediately backed it to build a daunting 4-0 lead.

Pliskova’s big serve was keeping her ahead in the key points - she struck seven aces during the first set and faced just one break point (she saved it with another timely ace). The No.4 seed calmly served out the first set, and carried her red-hot momentum into the second as she opened with another early break to create a 3-1 lead.

But Vekic’s patience paid off as Pliskova’s form took a dip - the unforced error count started to grow as Pliskova’s serve seemed to abandon her, giving Vekic the opportunity to get back in it.

Vekic finally broke the Pliskova serve for the first time to level at 3-3, and then turned the momentum around as she reeled off four games in a row to make it 5-3. Pliskova denied her set point, breaking back at 5-4 and, at 40-0 on her serve, looking ready to post a routine hold to tie up the scoreboard

But Pliskova’s service woes crept back into her game at the worst time - she had hit five double faults in three service games - and Vekic converted her second set point to take the match into a decider.

There was not much to separate them in the tense third set, but a lone break from Pliskova at 2-1 proved to be crucial. She was able to keep Vekic under pressure throughout, and she saved two break points to hold on to the lead. A final break sealed the match for Pliskova after a two hour and five minute battle.

“I don’t think my serve today was great,” Pliskova said. “I was getting tired from the match, so it was not as fast as I wanted to serve. But I won, that’s important, which means I have a chance to improve again.”

Through to her second final of 2018 and her first in Tokyo, Pliskova will take on the winner between US Open champion Naomi Osaka and the ever-dangerous Camila Giorgi in the next round as she seeks her second title of the season.

“The last match is always the toughest, but at least you know you can put everything into it,” she said. “But I also want to enjoy it, because it’s a final - you don’t play finals every week. I’ll try to enjoy, try to win and try to play my best tennis.

“It’s a good week for me here - I’ve never been in the final in Japan, so I have to enjoy it.”