Mexico City - Second seeded American Sloane Stephens defeated Japanese wild card Naomi Osaka 6-3, 7-5 to set up a semi-final clash in the Mexico Open with eighth-seeded Belgian Yanina Wickmayer, who upset third-seeded Russian Anastasia Pavlyuchenkova 6-3, 7-6 (7/3).
Slovakia's Dominika Cibulkova - who reached the quarters on a walkover when top-seeded Victoria Azarenka pulled out with a left wrist injury - advanced to the semis with a 3-6, 6-2, 6-3 win over sixth-seeded Swede Johanna Larsson.
Cibulkova next faces American Christina McHale, who defeated Croatian Mirjana Lucic-Baroni 6-4, 6-7 (7/9), 6-2.