World number three Naomi Osaka and top-ranked Ashleigh Barty were pushed to the brink on Wednesday, but both survived early exits at Melbourne Park, as Simona Halep cruised.
Japan’s Osaka was made to work hard against in-form Katie Boulter, but fought back for a 3-6, 6-3, 6-1 victory to reach the quarter-finals in the Gippsland Trophy.
She next meets Irina-Camelia Begu from Romania as she ramps up preparations for the Australian Open starting Monday.
“Today was really tough for me. It just felt like a new experience playing here again after such a long while,” Osaka said.
British world number 371 Boulter, who knocked out teenage sensation Coco Gauff Tuesday, ran her error-strewn opponent ragged to claim the first set in 39 minutes.
A refocused Osaka lifted her intensity to run away with the contest in a one-sided third set.
The three-time Grand Slam champion had comfortably beaten France’s Alize Cornet in straight sets on Tuesday in her first competitive match since lifting her second US Open title in September.
World number one Barty also had a fright in her match against Marie Bouzkova of the Czech Republic, but recovered from a second-set stutter to win 6-0, 4-6, 6-3.
Barty, hoping to break her country’s 43-year singles title drought at the Australian Open, will face Shelby Rogers of the United States next.
Reigning Australian Open champion Sofia Kenin was also pushed hard by American Jessica Pegula, dropping the first set and finding herself 4-1 down in the second before prevailing 5-7, 7-5, 6-2.
World number five Elina Svitolina also had to come from behind to beat 2017 French Open champion Jelena Ostapenko 6-7 (7/4), 6-3, 6-2.
She’ll next face 20th-ranked Belgium’s Elise Mertens, who knocked out Caroline Garcia of France 7-6 (7/1), 6-3.
World number two Halep bucked the trend and downed Laura Siegemund in straight sets to set up a Gippsland Trophy quarter-final against Russia’s Ekaterina Alexandrova who upset French Open champion Iga Swiatek 6-4, 6-2.