Caroline Wozniacki's love affair with the Toray Pan Pacific Open continued on Wednesday as she booked a quarter-final spot after beating Ana Konjuh in straight sets.

The Dane won the title in Tokyo in 2010 and has now made the last eight in five of her last six appearances, including a run to the final 12 months ago where she was beaten by Ana Ivanovic.

Despite glimpses of power from Konjuh, Wozniacki was in control of her second-round match and was able to keep her cool on the big points while her young opponent was inconsistent.

And it was a wayward shot down the line from Konjuh that secured Wozniacki's 6-2 6-2 victory, setting up a last-eight clash with fifth seed Angelique Kerber, who came from a set down to beat Madison Brengle.

Kerber struggled with her serve in the opener and a break in the 11th game enabled Brengle to move ahead, however the German quickly found her composure.

From 1-1 in the second set, Kerber turned on the style to win 11 straight games and complete a 5-7 6-1 6-0 victory.

Garbine Muguruza's long-awaited return to form continued with a 6-3 6-4 victory over Barbora Strycova, only the third win for the Spaniard since reaching the Wimbledon final.

Her quarter-final opponent will be eighth seed Belinda Bencic, after the rising star on the WTA Tour rallied from losing the opening set to beat Sam Stosur 6-7 (5-7) 6-3 6-4.