MADRID -- Iga Swiatek survived "one of the weirdest matches" after losing the first six games before recovering to defeat Madison Keys 0-6, 6-3, 6-2 on Wednesday and stay on track to defend her title at the Madrid Open.
The second-ranked Swiatek will face Coco Gauff in the semifinals after the 21-year-old American beat teenager Mirra Andreeva in straight sets in the youngest WTA 1000 quarterfinal since 2009.
Swiatek was overpowered by Keys early in their quarterfinal but eventually found a way to rally past the fifth-ranked American on center court.
"It was one of the weirdest matches I played," Swiatek said. "Maddie was playing just perfectly at the beginning, and I wasn't really proactive with anything. I let Maddie do more mistakes by just putting the ball back, and the momentum changed."
Swiatek said it didn't feel good to drop a set 6-0, noting "at least it was fast."
It was the first meeting between the two since Swiatek squandered a match point in their Australian Open semifinal that was won by Keys.
Swiatek is trying to reach her third straight Madrid final. She beat Aryna Sabalenka last year after losing to her in 2023. Swiatek hasn't gone past the semifinals at any tournament since last year's French Open.
Sabalenka, the No. 1 player in the world, later faces 24th-seed Marta Kostyuk in her quarterfinal match.
Gauff, ranked No. 4, won 7-5, 6-1 over seventh-ranked Andreeva, who turned 18 on Tuesday.
Since the introduction of the WTA 1000 tier, only the 2009 Indian Wells quarterfinal between Anastasia Pavlyuchenkova and Agnieszka Radwanska had a younger combined age, the WTA said.
Gauff recovered after being down a break at 5-4 in the first set. She faced two set points.
"Off the ground I think I was dictating most of the rallies, so happy with that," Gauff said. "Overall happy with everything."
Both Gauff and Andreeva had been able to finish their matches in the previous round just before play was paused because of the major blackout that brought Spain and Portugal to a standstill Monday. More than 20 matches had to be postponed at the Caja Magica tennis complex.
Matteo Arnaldi backed up his victory over Novak Djokovic in the second round of the men's draw by defeating Frances Tiafoe 6-3, 7-5 to reach the quarterfinals of an ATP 1000 tournament for the second time.
Arnaldi now has three consecutive wins against top-20 opponents for the first time in his career.
The Italian player will next face Jack Draper, who advanced by beating Tommy Paul 6-2, 6-2 in 68 minutes. The sixth-ranked Draper clinched his first ATP 1000 title in Indian Wells this year.