The Australian top seed came through the round-three clash in three sets, 6-3, 6-7, 6-2 at the National Tennis Center.

Zhang dropped just four games as she blew away American 13th seed Sloane Stephens yesterday but found Barty, this year's French Open champion, a tougher nut to crack.

"I made probably over 20 errors in that second set, which is disappointing," Barty said.

"Too many times I gave away cheap service games, but I'm happy with how we were able to respond in the third."

The women's China Open tournament is a Premier Mandatory event on the Women's Tennis Association circuit, and is played on hard courts.

Barty will now play two-time Wimbledon champion Petra Kvitová in the last eight after the Czech, seeded seventh, beat ninth seed Belinda Bencic of Switzerland 6-3, 6-3.

Third seed Elina Svitolina of Ukraine was taken to three sets by American Sofia Kenin before eventually triumphing 6-3, 6-7, 6-3 in a match which went beyond midnight. 

There was also a round-three win for Dutch eight seed Kiki Bertens, 7-6, 2-6, 6-3 against Slovenia's Polona Hercog.

Two second-round matches were completed today with Canada's 19-year-old fifth seed Bianca Andreescu making it through.

The teenager, who won her first grand slam after a shock triumph at the US Open in August, beat Belgium's Elise Mertens 6-3, 7-6.

American qualifier Jennifer Brady upset compatriot and 11th seed Madison Keys, beating the former US Open finalist 2-6, 6-4, 6-4.

The remaining third-round matches are tomorrow.