Thirty-five-year-old Anastasija Sevastova stunned the defending champion and No 3 seed on Friday, winning 3-6, 6-4, 6-1 in the round of 32.
Ranked 386, Sevastova was granted entry into the main draw with a protected spot after suffering a challenging knee injury.Â
She's the lowest-ranked player to beat someone in the top 10 since Angelique Kerber surprised Jelena Ostapenko more than a year ago at Indian Wells.
Sevastova wasn't sure how she pulled off the upset.
"Somehow, I was down 2-0 in the second set and started to play better and better," she said.Â
"Third set, I played really good. Just trying to stay on the court as long as possible."
"This was really about coming back and showing that you can do it after a torn ACL, after such a setback. It was like unfinished business."
The Latvian was playing only her 24th WTA Tour-level match in the past four years and had lost her last seven meetings against top five opponents.
Her last big result came at the 2018 US Open when she defeated Sloane Stephens in her best Grand Slam singles performance.
In the decisive third set, Sevastova scored two service breaks against Pegula to lock it up.Â
She was better in the big moments, saving nine of 13 break points and converting six of 10.
Sevastova can equal her best career result in Canada with a win on Sunday against Naomi Osaka who defeated Ostapenko 6-2, 6-4.
Osaka has won three matches in Montreal including a second-round struggle when she saved two match points against Liudmila Samsonova.
Don't Count Her Out �— wta (@WTA) August 1, 2025Madison Keys battles it out & defeats McNally 2-6, 6-3, 6-3.#OBN25 pic.twitter.com/S6OLovGVjO
Meanwhile, No. 6 seed and Australian Open champion Madison Keys came back to defeat fellow American Caty McNally 2-6, 6-3, 6-3 in two hours and 15 minutes.
Keys converted her third match point with a forehand pass, breaking McNally for the fourth time.
"Today I did a good job of bouncing back after the first set," Keys said.Â
"Let go of the first set and move on. Happy I was able to do that."
In the night session, Wimbledon champion Iga Swiatek of Poland routed Eva Lys of Germany 6-2, 6-2.Â
The second-seeded Swiatek advanced to face 16th-seeded Clara Tauson of Denmark, a 6-3, 6-0 winner over Ukraine's Yuliia Starodubtseva.
"It's always fun here. It was a solid match so I'm happy to have a chance to play another one here," Swiatek said.Â
"The match was different from how we played each other last time. I just focused on myself and knew what my plan was."
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