Guangzhou champion Wang, who has won 14 of her last 17 matches, next plays former world number one Karolina Pliskova or Aliaksandra Sasnovich.
World number three Angelique Kerber fought back from 5-3 down in the first set to beat Carla Suarez Navarro 7-6(4) 6-1.
Other News
U.S. Open champion Naomi Osaka crushed Danielle Collins 6-1 6-0 to set up a clash with 10th seed Julia Goerges who beat the Japanese the last time they met in Charleston this season.
American Sloane Stephens took advantage of an error-prone display by China’s Zheng Saisai to win 6-1 6-3 and set up a clash with Dominika Cibulkova who beat Daria Gavrilova 6-3 6-3.

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