Roger Federer took one step closer to a fourth Miami Open crown after defeating Canadian teenager Denis Shapovalov.
"It was a tactical match by me... I'm happy I was able to play with variations," said the 37-year-old Swiss, who won 6-2 6-4.
"I enjoyed it. I think I played very well. I had to. Because I think when you let Denis play, he's got some serious power, and he gets rhythm going. He can really put you in uncomfortable situations."
Defending champion Isner also bested a Canadian teenager, 18-year-old qualifier Felix Auger-Aliassime, 7-6 (3), 7-6 (4).

Arsenal manager Mikel Arteta extends contract until 2030
Silva, 40, comes out of retirement to join Hong Kong's Sha Tin
Ronaldo says Portugal coach broke his word, apologises to teammates
Messi signs off in tears after one last Argentina master class
Spain rally to beat Croatia, Kane shines for England in Nations League
