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).

Osaka and Swiatek reach US Open third round
Entries open for MENA Golf Tour Qualifying Schools
Slow start, strong finish as Alcaraz makes US Open third round
Dominant Sabalenka sweeps past Iatcenko to reach US Open third round
F1 champion Norris co-founds single-seater junior team
