Sloane Stephens followed Simona Halep out of the Sydney International after Yulia Putintseva served up a final-set bagel.

World number one Halep was beaten 6-4, 6-4 by Ashleigh Barty in her first competitive match since recovering from a back injury.

Stephens also failed to progress to the quarter-finals later in the day, the unseeded Putintseva beating the 2017 US Open champion 3-6 7-6 , 6-love.

Top seed Halep said she will head into the Australian Open, the first grand slam of the year, with no expectations after going down in straight sets to Barty.

Petra Kvitova will face defending champion Angelique Kerber in the last eight, having sent Hsieh Su-wei packing courtesy of a 7-6, 6-2 success.

Elise Mertens, Aliaksandra Sasnovich and Timea Bacsinszky were also second-round winners.