Teenager Mirra Andreeva reached her first Madrid Open final with a 6-4 7-6 (10-8) victory over Hailey Baptiste.
The 19-year-old Russian will face 26th seed Marta Kostyuk in Saturday’s final, after the Ukrainian beat Austria’s Anastasia Potapova 6-2 1-6 6-1.
Ninth seed Andreeva has won all bar one of her 13 clay-court matches this season, taking the title in Linz and reaching the semi-finals in Stuttgart, and becomes the first teenager to reach three WTA 1000 finals.
After taking the first set against the 30th seed, Andreeva served for the match at 5-4, but was broken by Baptiste who then took the second set to a tiebreak.
The 24-year-old American, who defeated world number one Aryna Sabalenka in the previous round, saved three set points before Andreeva completed her win.
“Honestly, I feel so much adrenaline inside. I feel like I’m still nervous. I’m just so happy that I won and that I was able to save all those set points,” said Andreeva, who has become the second-youngest finalist in the tournament’s history, behind Caroline Wozniacki.
“The serve helped me a lot. I’m so, so happy – I cannot really find ways to describe what I’m feeling right now,” added Andreeva.
Kostyuk advanced to her first WTA 1000 final in an error-strewn match against lucky loser Potapova, winning the first set with two breaks but losing the second in 30 minutes.
The 23-year-old raced to a 4-0 lead in the decider and refused to shake the hand of her Russian-born opponent after closing the match out.
In the men’s tournament, defending champion Casper Ruud was beaten in the quarter-finals by Belgian Alexander Blockx, 6-4 6-4.
Unseeded Blockx, who only broke into the top 100 for the first time last month and is at a career-high 69th in the world, has knocked out four consecutive seeds, including third-seeded Felix Auger-Aliassime, in the Spanish capital.
The 21-year-old defeated Ruud, the Norwegian 21st seed, in 96 minutes and will now face Alexander Zverev in his first tour-level semi-final, having never previously won a tour match on clay prior to this season.
Two-time Madrid champion Zverev won 6-1 6-4 against Italian 10th seed Flavio Cobolli, who beat the German en route to the Munich final 12 days ago, and has now reached the semi-finals in seven of his past eight Masters 1000 tournaments.
Top seed Jannik Sinner will face 21st seed Arthur Fils in Friday’s other semi-final after the pair won their quarter-finals on Wednesday.