ACAPULCO, Mexico -- 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.
The fourth-ranked Stephens, the 2017 U.S. 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.
In the men’s event at The Princess Mundo Imperial, top-seeded Rafael Nadal faced Nick Kyrgios in a night match.
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.