John Isner was broken in the first game but held thereafter and hit 16 aces to beat Albert Ramos-Vinolas 7-5, 7-6 (6) Sunday in the third round of the Miami Open.
Isner, now 33, won the biggest title of his career in the tournament a year ago. He is seeded seventh this year.
In women’s play, No. 25 Danielle Collins lost to Wang Yafan 7-5, 6-1.
Defending women’s champion Sloane Stephens was scheduled to play later Sunday, as was No. 1-ranked Novak Djokovic on the men’s side.