MASON, Ohio - Ashleigh Barty edged Anett Kontaveit 4-6, 7-5, 7-5 to reach the Western & Southern Open quarterfinals on Thursday.
The top-seeded Barty clinched it with a deep forehand winner. She raised her right fist in triumph after fighting off one match point and outlasting Kontaveit in 2 hours, 10 minutes.
Barty, the French Open champion and currently ranked second, can reclaim No. 1 by reaching the tournament final.
On the men's side, qualifier Yoshihito Nishioka followed up his upset of sixth-seeded Kei Nishikori by defeating Alex De Minaur 7-5, 6-4.
Venus Williams will play Donna Vekic, and Sloane Stephens will face Svetlana Kuznetsova in afternoon matches.