Coco Gauff followed up Olympic disappointment with an early Canadian Open exit after being stunned by Diana Shnaider in Toronto.

World number two Gauff suffered early eliminations at the Paris Olympics last week after falling in the singles, doubles and mixed doubles.

The number one seed was then downed 6-4 6-1 by her fellow 20-year-old, who secured the first top-10 win of her career to seal a maiden appearance in the quarter-finals of an ATP 1000 event.

"Sometimes I question like whether I should have played or not," Gauff said, "But at the end of the day I wanted to test myself and see if I would be able to, how I would do being mentally tired a little bit and physically fatigued.

"I said going into the tournament I didn't have high expectations, but I wish I could have competed better today, even if it resulted in a loss. I don't think I competed well."

Shnaider is a remarkable 39-14 across all professional matches for the year, winning three titles in Hua Hin, Thailand (hard) in February, Bad Homburg (grass) in June and Budapest (clay) in July.

"I know Coco is very physically prepared for everyone on tour, and she's running very well, she's covering all of the balls and all the angles on the court," Shnaider said.

"So when there were long rallies and I was winning them I was like, 'Wow, I just beat Coco in long rallies. I am good'. I mean, I tried to play it cool, but inside I was like, 'Yes! I made it!'"

Meanwhile, third seed Aryna Sabalenka eased past British number one Katie Boulter for a routine 6-3 6-3 triumph in Canada.

Sabalenka will next face Amanda Anisimova, one of five Americans in the last eight alongside defending champion Jessica Pegula, Peyton Stearns, Emma Navarro and Taylor Townsend.

Since the beginning of 2020, Sabalenka has reached 17 WTA 1000 quarter-finals, a feat only matched by world number one Iga Swiatek for the most at WTA 1000 events in that time.