No.1 seed Elise Mertens and unseeded Sorana Cirstea will face off for the TEB BNP Paribas Tennis Championship Istanbul title after both pulled off straight-sets semifinal wins.

Mertens ended the nine-match winning streak of No.3 seed Veronika Kudermetova, the Charleston champion and her doubles partner this week, 6-1, 6-4. Cirstea followed by coming from a break down in the second set to hold off rising teenager Marta Kostyuk 6-4, 6-4.

Sunday will be Mertens' 10th career final, and second of the season after her victory at the Gippsland Trophy in February. Cirstea, who reached her first final as a 17-year-old qualifier at Budapest 2007, has now booked her place in her fifth, and first since Tashkent 2019.

"She is in really good form," Mertens said about Kudermetova in her post-match press. "Her serve is extremely strong and that made it difficult, but I tried to attack when I had the opportunity. I hope the conditions will be a bit easier tomorrow and I can play well."

Mertens won another match later in the day, teaming up with Kudermetova to advance to Sunday's doubles final as well.

"It was a long day, so I'm glad I was able to finish both matches in straight sets," Mertens said.

Mertens was majestic in the first set against Kudermetova. Excelling with the dropshot and demonstrating superb point construction skills, the Belgian dropped just three points behind her serve while pushing her opponent to break point in every game, converting three times.

Kudermetova has displayed real grit all week, coming from 2-4, 0-40 down in the third set to best Bernarda Pera in a three-hour 6-4, 3-6, 7-6(4) first-round battle, then overcoming a 0-3 head-to-head to defeat Ana Bogdan 2-6, 6-3, 6-3 in the quarterfinals. Her record against Mertens was similarly bleak: Kudermetova had lost both of their junior meetings and all three of their pro encounters before today.

But despite struggling with consistency, particularly on the smash, the Russian made the second set more of a test for the top seed. Kudermetova twice went up a break, but was unable to consolidate either time.

Having clung on despite her own level dipping, Mertens took control again at the end of the set, coming up with another pair of hotshots en route to breaking Kudermetova for the match.

Before 2021, Kudermetova had never won a WTA semifinal - a barrier she broke through in style to reach the Abu Dhabi final in January. Today's result means that the World No.29 is now 0-5 in WTA 250 semifinals, but 2-0 in WTA 500 semifinals.

Cirstea is yet to drop a set this week, though both were tight against the talented but inconsistent Kostyuk. The Ukrainian teenager, who reached her own maiden semifinal in Abu Dhabi, was unable to complete a late comeback in the first or hold on to her leads in the second.

The Romanian took charge from the off, proving more solid as she leapt out to a 4-0 lead. But Kostyuk would surge back - only to miss a putative return winner by inches on a point to level at 5-5. In the second set, she twice went up a break, but could not consolidate as Cirstea's strategy of finishing points at net paid off.

"To be honest, I did not expect this," Cirstea admitted to the press, after her win. "I was hoping to come here and play a few matches and not think about the result at all. It makes me happy to be in the final and the happiest is the way I'm playing. I think I've played quite solid, and I feel like on any day I can be a tough opponent against anyone and this gives me a lot of hope for what's coming."

"I think this has always been one of my strengths, adapting quite quick, and this week we had to," Cirstea said. "There were so many different conditions. I had to bring out every single day a strong mindset and just think of my goal, no matter the conditions."

Looking forward to the final against Mertens, Cirstea said that the Belgian is "a very tough opponent, she's an established Top 20 player for a while already. I have a lot of respect for her because I've seen the way she improved over the years. And I see her every week and she works really hard and she's very smart in everything she does, so I think she deserves to be where she is."

Mertens ends Kudermetova winning streak to reach Istanbul final: Highlights

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