Team Europe beat Team World 15-9 to win the inaugural Laver Cup in Prague.
Europe began the final day with a 9-3 lead, but, after a win apiece in the opening two matches on Sunday, John Isner beat Rafael Nadal 7-5 7-6 (7-1) to cut the advantage to 12-9.
Roger Federer then went to a match tie-break with Nick Kyrgios, who had a chance to force a deciding doubles.
However, Federer saved match point and won 4-6 7-6 (8-6) 11-9 to spark jubilant celebrations.
The competition, which follows a similar format to the Ryder Cup, saw Federer and Nadal play doubles together for the first time on Saturday.
There was one point awarded for victories on day one, two for wins on day two and three for victories on the final day.
"It has been such an amazing and fun week and I'm so pleased the event has worked as it has," Federer, 36, said.
"The camaraderie in the group was amazing and we are all so happy. Time will tell how big the Laver Cup will become."