British number one Katie Boulter lost in straight sets against Aryna Sabalenka in the third round of the Canadian Open.
The second seed from Belarus won 6-3 6-3 in one hour 23 minutes but Boulter produced an encouraging performance with the US Open starting in two weeks’ time.
The 28-year-old created four break points against the world number three in Toronto but was unable to convert any.
Boulter, who reached the quarter-finals at the Olympic Games in the women’s doubles, will play her final warm-up tournament before the US Open at next week’s Cincinnati Open.
American top seed Coco Gauff is also out of the Toronto event as she surprisingly lost 6-4 6-1 against Diana Shnaider of Russia.
The defending US Open champion was knocked out in 70 minutes by the world number 66 and acknowledged she struggled physically and mentally.
“Sometimes I question whether I should have played or not,” Gauff said.
“But at the end of the day I wanted to test myself and see how I would do being mentally tired a little bit and physically fatigued.
“I didn’t have high expectations, but I wish I could have competed better, even if it resulted in a loss. I don’t think I competed well.”