US Open champion Samantha Stosur breezed into the quarter-finals of the HP Open on Thursday.
The Australian progressed in Osaka with a straight-sets defeat of home hope Misaki Doi.
The world number 113 fought hard but could not prevent Stosur from posting a 6-2 6-4 victory which sets up a quarter-final with South African Chanelle Scheepers.
Scheepers needed a final-set tie-break to see off qualifier Yaroslava Shvedova.
Shvedova claimed the opener but Scheepers hit back to win 4-6 6-3 7-6 (7/5).
Elsewhere, second seed Marion Bartoli, of France, dropped just three games as she beat American Vania King 6-1 6-2, while sixth seed Ayumi Morita kept home hopes alive with a 6-2 6-3 triumph over Greece's Eleni Daniilidou.
