GUADALAJARA, Mexico — Olivia Gadecki upset 2017 US Open champion Sloane Stephens 6-4, 6-3 on Monday to move into a second-round contest against second-seeded Danielle Collins at the WTA Guadalajara Open.

Seventh-seeded Veronika Kudermetova beat Sachia Vickery 6-4, 6-4 and advanced to meet Camila Osorio, the 22-year-old Colombian who eased past Hailey Baptiste 6-3, 6-2.

Local favorite Renata Zarazua had a 6-1, 3-6, 6-1 win over Anhelina Kalinina, and Kamilla Rakhimova advanced to face No. 3 seed Victoria Azarenka with a 7-5, 6-0 victory over Aleksandra Krunic.

Top seed Jelena Ostapenko, who is coming off a US Open doubles title victory with Lyudmyla Kichenok following her first-round loss to Naomi Osaka in the singles draw, won’t play until Wednesday.

The Guadalajara Open is a hardcourt 500-level event on the WTA Tour this season and is being played at the Complejo Panamericano de Tenis.