Argentina fought back to beat Croatia 3-2 and win the Davis Cup for the first time in a dramatic final in Zagreb.
Croatia led 2-1 going into the final day and looked on course for their second title when Marin Cilic led Juan Martin del Potro by two sets to love.
However, Del Potro staged a remarkable comeback to win 6-7 (4-7) 2-6 7-5 6-4 6-3 in four hours 53 minutes.
Federico Delbonis then swept past Ivo Karlovic 6-3 6-4 6-2 in the decisive fifth contest to clinch victory.
Argentina had lost in four previous finals but, roared on by a vociferous 1,500-strong group of travelling fans that included 1986 World Cup winner Diego Maradona, the visitors secured a stunning win.
Davis Cup final result: Croatia 2-3 Argentina
Friday: Marin Cilic (Cro) beat Federico Delbonis (Arg) 6-3 7-5 3-6 1-6 6-2
Juan Martin del Potro (Arg) beat Ivo Karlovic (Cro) 6-4 6-7 (6-8) 6-3 7-5
Saturday: Marin Cilic & Ivan Dodig (Cro) beat Juan Martin del Potro & Leonardo Mayer (Arg) 7-6 (7-2) 7-6 (7-4) 6-3
Sunday: Juan Martin del Potro (Arg) beat Marin Cilic (Cro) 6-7 (4-7) 2-6 7-5 6-4 6-3
Federico Delbonis (Arg) beat Ivo Karlovic (Cro) 6-3 6-4 6-2
Del Potro set the victors on their way from a seemingly desperate situation at two-sets down to world number six Cilic.
The victory capped a terrific year which has seen the 28-year-old return from four wrist surgeries to win Olympic silver and beat the likes of Novak Djokovic, Stan Wawrinka and, in the quarter-finals of the Davis Cup, Andy Murray.
"This was an emotionally exhausting match and one of the biggest wins of my career," said Del Potro.
"Thanks to all those who prevented me from retiring; I was very close to never playing again and, well, here I am."
Argentina captain Daniel Orsanic added: "His comeback is the comeback of history, his comeback today was the comeback of the Davis Cup.
"He's a genius. His heart is so big."
Delbonis is ranked 21 places below Karlovic at 41 in the world but brilliantly returned the 6ft 11in Croat's huge serve.
"He was on top of every ball," said Orsanic. "He played a perfect match. I'm surprised, in a good way. I thought he couldn't win so easy."