Brazilian qualifier Beatriz Haddad Maia beat top-seeded Sloane Stephens 6-3, 6-3 on Wednesday in the Mexican Open for her first victory in seven career matches against players ranked in the top 10.

Sloane Stephens of the US serves against Brazil's Beatriz Haddad Maia in their Mexican Tennis Open round 2 match in Acapulco, Mexico, Wednesday, Feb. 27, 2019. (Photos: AP)

The fourth-ranked Stephens, the 2017 US Open, was making her first appearance in the hardcourt event since winning the 2016 title.

The 22-year-old Haddad Maia will face Monica Puig or Wang Yafan in the quarterfinals.

Third-seeded Donna Vekic beat Christina McHale 6-4, 7-5, and seventh-seeded Saisai Zheng topped Timea Babos 4-6, 6-4, 6-3.

In the men's event at The Princess Mundo Imperial, top-seeded Rafael Nadal faced Nick Kyrgios in a night match. The second-ranled Nadal is playing his first event since losing the Australian Open final to Novak Djokovic. Nadal won in Acapulco in 2005 and 2013.

In the day session, third-seeded John Isner beat fellow American Sam Querrey 6-4, 6-4 to set up a quarterfinal match against eighth-seeded John Millman, a 6-0, 6-2 winner over Peter Gojowczyk.

Defending champion Juan Martin del Potro is sidelined by a knee injury. Lesia Tsurenko, the women's winner the last two years, is skipping the event.

Cover image: John Isner of the US returns a ball to Sam Querrey of the US at their Mexican Tennis Open round 2 match in Acapulco, Mexico, Wednesday, Feb. 27, 2019.