Top-seeded Coco Gauff tumbled out of the National Bank Open on Friday, falling 6-4, 6-1 to 14th-seeded Diana Shnaider in windy conditions at Sobeys Stadium. Preparing for her U.S. Open title defense, Gauff was broken trailing 5-4 in the first set. The 20-year-old American double-faulted down 2-1 in the second and Shnaider held serve to go up 4-1. “I just wasn´t finding my timing well,” said Gauff, the No. 2-ranked player in the world. “I had a lot of unforced errors and a lot of double faults. She played steady and she didn´t give me any free points. She was playing her first hard-court event since April. “I question whether I should have played (in Toronto) or not, but I wanted to test myself,” Gauf said. “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, also 20, sealed the victory with another break to set up a quarterfinal match against No. 6 Liudmila Samsonova, a 6-2, 6-4 winner over Elise Mertens. “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 today.´ I tried to play it cool, but inside I was like, `Yes! I made it!´” In the late match, No. 2 Aryna Sabalenka beat Katie Boulter 6-3, 6-3.