John Isner ended Juan Martin del Potro's hopes of a Sunshine Double as the American powered his way into the Miami Open final.
The world No 17 arrived in Florida with a mere two wins so far this season but extended his run at Crandon Park with a 6-1 7-6 (7-2) victory to become the first American into the Miami showpiece since 2010 champion Andy Roddick.
He will play German fourth seed Alexander Zverev, who beat Spaniard Pablo Carreno Busta 7-6 (7-4) 6-2 later on Friday.
Del Potro, who had won consecutive titles in Acapulco and at Indian Wells, led the head-to-head 6-3 but struggled to cope with Isner's big serving and aggressive baseline strategy as the 32-year-old prevailed in 83 minutes.
"I played extremely well. This is a level of play I know I am capable of, it is just much easier said than done to go out on the court and perform that way," Isner told Sky Sports.
"I think I might have discovered something this week and certainly something that I can build on for the future. I love the way that I am playing. Playing like this, I am a very tough out, so I just want to keep it going."
Isner raced through the first set in 26 minutes with an authoritative all-court display as the big-serving American mixed 19 winners with six aces to secure two breaks against an out of sorts Del Potro.
The Argentinian began the second set with a winner - something he hadn't managed at all in the opener - and showed why he came into the encounter on a 15-match winning streak, as both players held their serve to force a tie-break.
Isner secured the early mini-break and celebrated victory on his first match point with another winner at the net to reach his fourth Masters 1000 final.
After a first set which followed serve, Zverev immediately lost serve as Carreno Busta took the advantage but the German held strong winning the last three points, two against serve, to take the set.
The second was a shorter affair, the world No 5 breaking for 2-1 and 5-2 before serving to love for the match.
"I didn't feel I was playing my best in the beginning of the first set, a lot of errors." Zverev said in an on-court interview.
"I was down in the tiebreak and I was like, I'm losing anyway I might as well be aggressive. So that's what I did, I hit a few winners, very fortunate to win the first set and then found my game in the second."
You can watch live coverage of the final of the ATP 1000 Miami Open from 6pm on Sunday on Sky Sports Arena or Mix.
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