John Isner finally put an end to his ATP Masters final agony on Sunday, winning the Miami Open for the first time by beating Germany's Alexander Zverev 6-7 (4/7), 6-4, 6-4.

The 14th seed had lost his previous three major tour final appearances in 2012, 2013 and 2016 but came back from a set down to beat Zverev in two hours and 29 minutes.

The victory capped a superb tournament for Isner, who endured a difficult start to 2018 which included an early-round exit at Indian Wells in his lead-in to Miami.

"I couldn't have scripted this. I came into this tournament, I won one ATP [World Tour] match all year and was playing very poorly," Isner said after his win. 

"I won my first match in three sets and that's how tennis goes - you start to gain a little confidence and next thing you know things start to roll your way."

Isner is the first US player since Andy Roddick in 2010 to lift the Miami title.

Isner will also reclaim a career high world ranking of ninth after the victory, the 13th title of his career.

Both Zverev and Isner were faultless in their service games and the first set predictably went the distance before fourth seed Zverev prevailed when Isner sprayed a backhand wide.

The break, however, finally came for Isner at 4-4 in the second set and when Zverev, who missed the chance to return to number three in the world with this defeat, failed to hold at 5-4 in the third, Isner sealed the best win of his career with an ace.