China's Zheng Qinwen progressed to the round of 16 of the Miami Open on Saturday with a 6-1, 7-6(3) win over American Taylor Townsend.

Olympic gold medalist Zheng won 80 percent of her total service points and converted two of three break points to take the match in an hour and 17 minutes.

Townsend struggled to deal with the power and accuracy of the ninth seed's serve, winning just 11 of 55 points on her return.

Zheng's next match will be against American Ashlyn Krueger, who registered a straight sets win over Canada's 26th seed Leylah Fernandez in their third-round encounter.

Zheng, 22, is aiming for her sixth career title in the WTA 1000 hardcourt event.