After John Isner clinched his berth in the Miami Open final, he came over the top one last time, throwing a celebratory punch at a speed to match his thunderous serve.
The towering American moved one step closer to the most prestigious title of his 14-year career by beating a weary Juan Martin del Potro 6-1, 7-6 (2) in the semi-finals.
"I'm playing the best tennis I've played in a very, very long time," said Isner, 32.
"And I'm so happy to be doing it here."
Dominating with his serve and aggressive baseline strokes, the 6-foot-10 Isner ended a 15-match winning streak for del Potro, who won Indian Wells two weeks ago by beating Roger Federer in the final.
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The toll of so many matches showed, and Isner was the better player from start to finish.
Seeded No. 14, Isner is 0-3 in ATP Masters 1000 finals.
His opponent Sunday will be No. 4 Alexander Zverev of Germany, who beat No. 16 Pablo Carreno Busta of Spain 7-6 (7-4) 6-2.
Zverev, 20, has won two Masters 1000 titles, both in 2017.
Isner is seeking to become the first American man to win Key Biscayne since Andy Roddick in 2010.
"When he plays as good as today, he's one of the tougher guys on the tour," del Potro said. "He has everything to win a title like this."
