World number four Naomi Osaka will take on Yulia Putintseva of Kazakhstan in the quarter-final of the Toray Pan Pacific Open on Friday.
USA's Madison Keys will take on Germany's Angelique Kerber, while Japan's Misaki Doi will face Anastasia Pavlyuchenkova of Russia. In the fourth quarter-final, Camila Giorgi of Italy will take on Belgium's Elise Mertens.
On Thursday, Camila Giorgi dropped just three games to upset third-seeded Sloane Stephens. The unseeded Italian, who reached the semi-final last year, beat the 2017 US Open champion 6-0, 6-3.
Misaki Doi upset seventh-seeded Donna Vekic 7-6 (5), 6-3 to reach the last eight, whereas Yulia Putintseva defeated qualifier Varvara Flink 6-1, 6-1.
Naomi Osaka reached the quarters by beating qualifier Viktoriya Tomova 7-5, 6-3, while fourth-seeded Angelique Kerber won her first match since Wimbledon, beating American qualifier Nicole Gibbs 6-2, 6-4.
Madison Keys defeated Zarina Diyas 5-7, 6-0, 6-4, as Elise Mertens beat Hsieh Su-Wei 6-3, 1-6, 6-2.