Aryna Sabalenka, Iga Swiatek advance to semifinals at Madrid Open

Last year's runner-up Aryna Sabalenka survived a gritty Marta Kostyuk and an untimely rain interruption to complete a 7-6(4), 7-6(7) win over the Ukrainian and reach the Madrid Open semifinals for a fourth time on Wednesday.

Top-seeded Sabalenka needed 84 minutes to take the opening set before securing the win in cold, breezy conditions.

Kostyuk saved a match point and broke to take the second set into a tiebreak. At 5-4 in the breaker, it started to rain and play was halted briefly to close the roof of the Manolo Santana stadium.

Upon resumption of play, Sabalenka saved three set points and eked out the win, her third over her rival in as many meetings.

"Honestly, that was a battle and conditions were incredibly tough. It wasn't about tennis, it was about the way you handled your emotions," said the Belarusian world No. 1, who hit 48 unforced errors. "I think I did really well and I'm super proud I was able to handle myself in such a difficult situation."

Sabalenka will next take on another Ukrainian in the form of Elina Svitolina, who extended her winning streak to 11 consecutive matches with a swift 6-2, 6-1 rout of Japan's Moyuka Uchijima in just 52 minutes.

A champion in Rouen last week, Svitolina remains undefeated on clay this season and is the first Ukrainian woman to reach the semi-finals in Madrid. The 30-year-old has won her last 22 consecutive sets on the red dirt.

Earlier in the day, Iga Swiatek kept her Madrid Open title defense alive, as she avenged her Australian Open defeat to Madison Keys with a 0-6, 6-3, 6-2 win against the American in the quarterfinals.

The second seed will next square off with Coco Gauff, who beat 18-year-old Mirra Andreeva for the third time in as many meetings, 7-5, 6-1.

Searching for her first title of the season, second-seeded Swiatek recovered from a poor opening set to improve her clean record on clay against Keys to 4-0 and reach a third consecutive Madrid semifinals.

Keys knocked out the Pole on her way to a maiden Grand Slam title in Melbourne three months ago and seemed to have cracked the Swiatek code when she handed her a bagel in the first set on Wednesday.

Nonetheless, Swiatek, who was contesting a 17th consecutive quarter-final on clay, cut down on her errors and struck back to book a last-four clash with Gauff.