Serena Williams lost the opening set of her second-round match against 17-year-old Caty McNally before coming back to win, then was much better in a convincing 6-3, 6-2 victory over Wimbledon quarterfinalist Karolina Muchova.

Williams seized control with a seven-game run that began after she trailed 3-2 at the beginning.

"I knew what she could do," Williams said — after not allowing Muchova to do much.

She'll face No. 22 Petra Martic on Sunday for a spot in the quarterfinals.

Other women's winners Friday included No. 2 Ash Barty, No. 3 Karolina Pliskova, No. 5 Elina Svitolina, No. 10 Madison Keys and No. 16 Johanna Konta. Keys, the 2017 runner-up in New York, had her blood pressure and pulse checked during a second-set medical visit but held on to beat No. 20 Sofia Kenin 6-3, 7-5 in an all-American matchup.