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).

Iran will be at World Cup and will play in the US, says FIFA boss
Abu Dhabi advises fans to arrive early for Al Ain, Al Wahda match
Sangakkara, Mahanama named in interim committee to run Sri Lanka Cricket
Focused Fils making a statement ahead of French Open
Atletico hit back to hold Arsenal in cagey Champions League semi-final first leg
