The WTA's Japan Open quarter-finals will include unseeded defending champion Christina McHale and Kazakh qualifier Zarina Diyas.
Defending champion Christina McHale has advanced to the quarter-finals of the Japan Open with a straight-sets win over Sara Sorribes Tormo.
American McHale dominated with solid groundstrokes and took advantage of 10 double-faults by her Spanish opponent in the 6-1 6-1 victory.
McHale will meet Elise Mertens of Belgium in the last eight.
Upsets continued on Thursday when Kazakh qualifier Zarina Diyas beat second-seeded Zhang Shuai 6-4 6-2.
A day after ousting top-seeded Kristina Mladenovic, Croatia's Jana Fett booked her spot in the next round with a 6-0 6-3 win over Jana Cepelova of Slovakia.
Eighth-seeded Yulia Putintseva advanced after an abbreviated second-round match. She was leading 6-2 2-0 when Han Xinyun retired because of injury.
China's Wang Qiang overpowered local favourite Kurumi Nara 6-2 6-3.