Marta Kostyuk described the second set of her Madrid Open semi-final with Anastasia Potapova as "weird" but was thrilled to overcome adversity to reach the showpiece match.

Kostyuk will take on Mirra Andreeva in Saturday's final following a 6-2 1-6 6-1 victory over lucky loser Potapova in what was an entertaining affair in the Spanish capital.

The Ukrainian took control early on, saving two break points to hold for a 3-0 lead and capitalised on Potapova's erratic start to take the first set in just 35 minutes.

However, Potapova flipped the momentum in the second, with Kostyuk making 17 unforced errors and winning only 18% of her first-serve points to take the match the distance. 

"The second set was really weird today," Kostyuk said. "I hadn't dropped a set all week, so to lose a set felt kind of weird.

"But I'm very proud of how I managed to keep supporting myself. I wasn't playing the way I always play today, but I felt like this was the key, and she didn't like it.

"The match that we had last year was entirely different. I think she played very differently, and the conditions were in her favour a bit today because the balls were extremely heavy, and they were not picking up my spin.

"So she stayed very far from the baseline. And yeah, I tried different things. Clearly, what I was doing in the second set didn't work, but I'm incredibly happy with the turnaround."

Kostyuk swung the pendulum back in her favour in the third set, reeling off the opening four games before Potapova got herself on the board, but it was too little, too late. 

The Austrian could not convert any of the three break points she created for herself in the sixth game, with Kostyuk seeing out the contest with the minimum of fuss. 

Kostyuk's win saw her become only the third Ukrainian to reach a Tier I / WTA-1000 final since the format's introduction in 1990, after Elina Svitolina and Anhelina Kalinina.

In addition, only world number one Aryna Sabalenka (four) has made more WTA level finals than Kostyuk in 2026 (equalling Elena Rybakina and Andreeva).

"Even in tough moments today, I really tried to enjoy this moment being in the semifinals here," Kostyuk added.

"And no matter how it would turn out, I really just – in 20-30 years, I want to think about this moment and really smile about it.

"Don't remember the misery or being hard on myself, because at the end of the day, we all go out on court, and we do our absolute best always. And I did that."

Only two players have claimed 10+ WTA level clay court wins in 2026: the Madrid Open's finalists (Andreeva with 12 and Kostyuk with 11, including the Billie Jean King Cup).