Samantha Stosur beat Belinda Bencic 6-4, 6-2 at the Japan Open on Wednesday and became the highest remaining seed after Wimbledon runner-up Sabine Lisicki withdrew hurt.
No. 2-seeded Lisicki hurt her left hip, and pulled out from her scheduled second-round match with Polana Hercog, who advanced to a quarterfinal with local wild card Kurumi Nara.
Stosur, the No. 3 seed, reached her first quarterfinals since her title run in Carlsbad in August. She lost her serve twice but broke Bencic five times at Utsobu Park and will next face either Kimiko Date-Krumm or Misaki Doi in the last eight.
Stosur won in Osaka in 2009 and was runner-up in 2011 and a semifinalist in 2012.
In other second-round matches, Nara beat eighth-seeded Monica Puig 7-5, 7-6 (4), and fifth-seeded Eugenie Bouchard overpowered Luksika Kumkhum 6-2, 6-2. Qualifier Barbora Zahlavova Strycova defeated Vania King for the second time this year, 2-6, 6-3, 6-1, and will meet Bouchard next.