Garbine Muguruza received a walkover past Victoria Azarenka after the Belarusian withdrew before their round of 16 match at the Chicago Fall Classic.
In the quarter-finals, Muguruza will face surprise qualifier, 22-year-old Japanese Mai Hontama, who beat Shelby Rogers, 6-4, 6-7(1), 6-1.
Hontama is ranked No.200, but that has not stopped her causing a few upsets, she cruised past former World No.4 Caroline Garcia, 6-3, 6-0 in the opening round.
Meanwhile, No.5 seed Elena Rybakina picked up a third career win against Veronika Kudermetova 7-6(4), 7-5 in an all-Russian match-up.
