Isner won his maiden Masters 1000 title this evening in scorching conditions at Key Biscayne.
He came from behind to prevail in three sets – 6-7, 6-4, 6-4 – as Crandon Park was given a fitting farewell after staging the tournament for 31 years.
In doing so, Isner will jump to a career-high of world No 9 when the rankings are published tomorrow and he will regain the mantle of No 1 American.
Isner also became the oldest first-time winner of an ATP Masters 1000 event in clinching his first win over Zverev, who entered the tournament fifth in the ATP standings.
And the 32-year-old thinks Zverev, who has struggled to make an impact on the Grand Slams, will reach the summit of the men’s game one day.
“We have known each other for seven to eight years now,” Isner said.
“I was practising with him when he was 14 and I knew he was going to be the next big thing in tennis.
“He has won two of these before so I appreciate you letting me have one.
“You have the brightest future ahead of you and the greatest team with you. You do everything the right way.
“I see the work you put in. You deserve everything you have accomplished so far and everything you will accomplish in the future.
“Keep pushing along and you are going to be at the very top one day.”
