Former world No 1 Victoria Azarenka advanced to the last eight in a postponed women's match of Washington Open, dispatching Czech Tereza Martincova 7-6 (9/7), 6-2 on Friday.
World number 20 Azarenka, 33, won an 80-minute first set then dominated the second to secure her first WTA quarterfinal berth since January in Adelaide.
Azarenka, a two-time Australian Open champion and three-time US Open runner-up, was set for her second match of the day, against Chinese lucky loser Wang Xiyu, for a semifinal spot.
Estonia's Kaia Kanepi defeated Anna Kalinskaya 6-7 (4/7), 6-4, 6-3 to reach the semifinals.
Kanepi, her age and world rank at 37, seeks her fifth career WTA title but first since the 2013 Brussels Open. Her only hardcourt title came at Brisbane in 2012.