(AP) — Sloane Stephens knows how it feels to win a championship. She can't wait to do it again.

Stephens got started on a second Tuesday, rolling to a 6-1, 6-2 upset of 10th-ranked Carla Suarez Navarro in the first round of the Western & Southern Open. She won the first title of her pro career at the Citi Open on Aug. 9 in Washington.

"(You're) always like searching and trying to find that next great moment, and like that was like one Sunday where I had a great moment," said the 22-year-old Stephens, a first-round loser at Toronto last week. "Now, I'm like, 'I need another Sunday. Come on.'"

The 30th-ranked Stephens served nine aces to Suarez Navarro's two.

"Nine aces today — boom," she said with a wave of her hand. "I'm working on a lot of things, but that is definitely one thing that I have tried my best to improve on. It's coming around, so that's good."

Daria Gavrilova also pulled off an upset, surprising 16th-seeded Sara Errani 6-1, 4-6, 6-2.

In other women's play, Kristina Mladenovic advanced with a 6-2, 6-1 win over wild-card Daniela Hantuchova and Flavia Pennetta topped Dominika Cibulkova 7-5, 6-2.

In first-round men's action, Richard Gasquet cruised past Nick Kyrgios 6-2, 6-1, while Tommy Robredo ousted fellow Spaniard Pablo Andujar 3-6, 6-3, 6-1 and Kevin Anderson outlasted Leonardo Mayer 7-6 (5), 3-6, 6-1.

Wild-card Jared Donaldson eliminated qualifier Nicolas Mahut 7-5, 6-7 (2), 6-2, finishing a match suspended Monday because of darkness.