"It was not my best start," Muguruza said. "I had to come back and bring something different to the match because it wasn't going my way. "I think she was playing great, but I just had to wait for my opportunities, and stay in the match."
Muguruza will next face Shelby Rogers for a place in the quarterfinals. Rogers beat Nicole Gibbs 6-3, 5-7, 6-4. Also, defending champion Aryna Sabalenka defeated Margarita Gasparyan 6-3, 6-0, while seventh-seeded Elena Rybakina held on to beat Saisai Zheng 6-2, 1-6, 6-2.
Aliaksandra Sasnovich, Kristyna Pliskova, Qiang Wang and Peng Shuai also won.
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