Third-seeded Samantha Stosur beat Swiss qualifier Belinda Bencic of Switzerland 6-4, 6-2 at the Japan Open on Wednesday to reach her first quarter-finals since her title run in Carlsbad in August.
Stosur 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, fifth-seeded Eugenie Bouchard of Canada overpowered Luksika Kumkhum of Thailand 6-2, 6-2 while local wild card Kurumi Nara beat eighth-seeded Monica Puig of Puerto Rico 7-5, 7-6 (4).
Czech qualifier Barbora Zahlavova Strycova defeated Vania King of the United States for the second time this year, 2-6, 6-3, 6-1, and will meet Bouchard next.