TORONTO (AP) — Top-seeded Coco Gauff was eliminated from the National Bank Open after losing 6-4, 6-1 to 14th-seeded Diana Shnaider in windy conditions at Sobeys Stadium on Friday.

Gauff, who is defending her US Open title, was broken after trailing 5-4 in the first set. The 20-year-old American double-faulted after trailing 2-1 in the second set and Shnaider held serve to take a 4-1 lead.

“I didn’t get my timing right,” said Gauff, the world’s No. 2 player. “I made a lot of unforced errors and double faults. She played consistently and didn’t give me free points.

It was her first time playing on hard court since April.

“I question whether I should play (in Toronto), but I wanted to test myself,” Gauf said. “I didn’t have high expectations, but I would have liked to have competed better today, even if it ended in a loss. I don’t think I competed well.”

Shnaider, also 20, clinched the win with another break to advance to her match against No. 6 Liudmila Samsonova, who beat Elise Mertens 6-2, 6-4 in the quarterfinals.

“I know Coco is very physically ready for everyone on the tour, and she runs very well, she covers every ball on the court and every angle,” Shnaider said. “So when there were long rallies and I won them, I was like, ‘Wow, I beat Coco in long rallies. I’m good today.’ I tried to act calm, but inside I was like, ‘Yeah! I did it!'”

Late in the match, No. 2 seed Aryna Sabalenka defeated Katie Boulter 6-3, 6-3.

Earlier, defending champion Jessica Pegula defeated qualifier Ashlyn Krueger 6-2, 6-4.

Pegula, the third-seeded player from nearby Buffalo, N.Y., took advantage of Krueger’s nine double faults. Last year in Montreal, Pegula beat Samsonova in the final.

In the quarterfinals, she will face Peyton Stearns, who became the fifth American to win after No. 12 Victoria Azarenka retired with a thigh injury.

Taylor Townsend beat fourth seed Jelena Ostapenko 6-2, 6-1, while eighth seed Emma Navarro beat 11th seed Marta Kostyuk 7-5, 7-5 to set up a quarterfinal match.

Amanda Anisimova advanced to the next round after No. 10 Anna Kalinskaya of Russia withdrew due to dizziness. Anisimova won the first set 6-2. She will face Sabalenka in the quarterfinals.

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Gauff is one of several Top 10 players who have chosen to make the jump to Toronto hardcourts immediately after playing the Olympics on the red clay of Roland Garros. It was important for Gauff to establish a foundation for the North American hardcourt season, which continues next week in Cincinnati and is followed by the US Open, where Gauff defends her title.