Coco Gauff begins road to US Open with win in Toronto; Elise Mertens beats Naomi Osaka

TORONTO (AP) — Top-seeded Coco Gauff routed Yafan Wang 6-4, 6-2 on Thursday in the second round of the National Bank Open.

Preparing for her US Open title defense, Gauff played her first hard-court match since the Miami Open in April.

"It's not easy transitioning from all these different surfaces in such a short amount of time," said the 20-year-old American, coming off a third-round loss on clay in the Paris Olympics. "Happy to get pushed through."

In the night session, second-seeded Aryna Sabalenka, the Australian Open winner, beat Yue Yuan 6-2, 6-2.

"I wouldn't say that I played my best tennis," Sabalenka said. "Really happy that I was able to stay focused no matter what."

Elise Mertens edged Naomi Osaka 6-3, 6-4 in a late match. Osaka, a former No. 1 player with four Grand Slam titles, is returning to form following maternity leave.

Earlier, fourth-seeded Jelena Ostapenko outlasted Paula Badosa 3-6, 7-6 (3), 6-2. Badosa won the Washington title Sunday in her comeback from a back injury.

No. 5 Daria Kasatkina, No. 6 Liudmila Samsonova, No. 8 Emma Navarro and No. 10 Anna Kalinskaya advanced. No. 7 Madison Keys retired from her match against Peyton Stearns because of a thigh injury while down 3-0 in the third set.

Kasatkina beat Amanda Anisimova 6-4, 6-3; Samsonova topped Moyuka Uchijima 6-4, 6-2; Navarro beat Magda Linette 6-2, 6-4; and Kalinskaya edged Lesia Tsurenko 6-2, 6-2.

Canadian Leylah Fernandez, seeded 15th, dropped out with a 6-4, 6-2 loss to qualifier Ashlyn Krueger. Marina Stakusic, a 19-year-old wild card from nearby Mississauga, was thumped 6-0, 6-2 by Taylor Townsend.