The two-time Grand Slam champion Muguruza had a brief bout of nerves and was down a double break before she raised the level of her play to win the match in 78 minutes.
“It was a very difficult match especially in the second set as I was down 0-4. She had a lot of advantages but I’m happy that I kept fighting and ended up winning,” said the 2016 French Open and 2017 Wimbledon winner.
Eighth seeded Dayana Kastremska of Ukraine reached her second quarter-finals of the year following a 6-1 6-4 over wildcard holder Peng Shuai of China.
“In the first set I felt really well on court but in the second set I felt a bit weak. But I tried to keep myself under control and stayed focused like I did in the first set which is the key for me to take the second set,” added the 18-year-old Ukrainian who also reached this stage in a WTA event in Hobart earlier this month.
She will play Muguruza whom she beat 6-2 6-3 in the second round in Luxembourg last year.
“I beat Muguruza last year. It will be a tough match. I have to be well prepared and try my best,” the WTA Hong Kong Open champion in 2018 said.
Asked about a re-match with the teenage rival, Muguruza said: “She is young and has nothing to lose. She is playing well right now, it will be a tough match.”
In other second round matches, fourth-seeded Saisai Zheng of China beat Irina-Camelia Begu of Romania 6-2 6-4 while sixth seed Ajla Tomljanovic of Australia beat Kateryn Kozlova of Ukraine 7-6 (7-0) 6-1.