Ekaterina Alexandrov took down four-time Grand Slam singles champion Aryna Sabalenka in a three-set marathon in Toronto.

World number one ‌Aryna Sabalenka suffered a setback in her US Open ⁠build-up after ⁠she was beaten 7-6(3), 4-6, 6-4 by Russia’s Ekaterina Alexandrova in the fourth round of the Canadian Open ⁠in Toronto on Saturday.

The 16th-seeded Alexandrova fought a hard battle, lasting nearly two and a half hours, to secure her quarterfinal berth.

Sabalenka, a four-time Grand Slam champion and reigning US Open winner, recovered from a set down to force a decider but was unable to halt Alexandrova’s aggressive shot-making in the final set.

The Belarusian ‌broke early in the opening set before Alexandrova rallied to force a tiebreak, which the Russian won to move ahead.

Sabalenka responded by seizing control of the second set with a break for a 4-3 lead before serving out to level the match.

Alexandrova held her nerve in the decider as ⁠Sabalenka’s error count rose. Serving to stay ⁠in the match at 4-5, the top seed saved two match points, but a double fault on the third handed victory to the Russian.

“I just tried to ⁠play every single point as if it was the last one because with her, you ⁠don’t [get] a lot of chances during ⁠the match,” Alexandrova said in her on-court interview.

“Honestly, I was trying not to think about the score or anything. Just hit the ball, and that’s it.

“I’m super ‌happy that I could win because after the second set, I thought (the chance) was already past me.”

Alexandrova will face Ukraine’s Elina ‌Svitolina, ‌who defeated American eighth seed Amanda Anisimova 6-2, 6-4 for a place in the semifinals.