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).

Al Nassr secure semi-final spot in AFC Champions League 2 with victory over Al Wasl
Advantage Man City as Haaland seals crucial win over Arsenal
Bayern Munich win Bundesliga title with victory against VfB Stuttgart
Fils powers past Rublev to win Barcelona Open
Liverpool's Van Dijk scores late winner in derby win over Everton
