Top seed Simona Halep needed three sets to overcome Caroline Garcia and reach the quarter-finals of the Apia International Sydney following an injury scare last week.
An Achilles problem forced the Romanian to withdraw from the Brisbane International in Queensland, but she was fit enough to defeat Garcia 6-4 2-6 6-1 at the WTA Premier event on Tuesday.
Although the world number two only gave up her serve twice in the match, that came in the form of a costly double break late in the second set, forcing a decisive third at the NSW Tennis Centre.
Halep responded well though, breaking Garcia three times and holding throughout that set to book a meeting with Karolina Pliskova in the last eight.
Fourth seed Angelique Kerber, a beaten finalist in Sydney two years ago, became the latest member of the women's top 10 to suffer illness or injury in the lead-up to the Australian Open, a gastrointestinal problem prompting the German to pull out, handing Ekaterina Makarova a walkover victory.
Of the other seeds in action, Belinda Bencic (8) defeated wildcard and 2014 winner Tsvetana Pironkova 6-3 6-3, while last year's runner-up Pliskova (5) dispatched Anastasia Pavlyuchenkova 6-3 6-0.
Home favourite Sam Stosur, who lost an all-Australian Sydney final to Alicia Molik in 2005, saw off qualifier Daniela Hantuchova 6-4 6-2.
Svetlana Kuznetsova, the 2008 runner-up, needed three sets to get past Sabine Lisicki 6-3 3-6 6-2, while Sara Errani battled past 2007 finalist Jelena Jankovic 7-6 (7-3) 7-6 (10-8).
Qualifier Monica Puig defeated Anna Karolina Schmiedlova in straight sets.