After Rafael Nadal earned a dominant win over Juan Monaco in the first match, Ferrer looked to be in trouble after Del Potro went ahead 2-1 in sets. But the Argentine seemed to struggle with fatigue and nerves down the stretch, double-faulting on set point in the fourth to force a decider.
Ferrer then jumped out to a 5-1 lead before clinching the victory with his 28th forehand winner.
Nadal eased to a 6-1, 6-1, 6-2 win over Monaco earlier Friday, and Feliciano Lopez and Fernando Verdasco can close out the series for four-time champion Spain against David Nalbandian and Eduardo Schwank in Saturday’s doubles.
The United States is the only nation to have rallied from a 2-0 deficit in the final, in 1939 at Australia.
Ferrer dropped to his knees and let out a long scream after winning a nearly five-hour match to leave the South Americans on the verge of failing for the fourth time in a final.
Ferrer’s comeback looked unlikely after Del Potro took control in the second and third set, with the former U.S. Open champion’s booming forehand dictating many of the rallies. Of Del Potro’s 71 total winners, 39 came from his forehand as the cold conditions favored the lanky Argentine’s game.
But with Nadal and Spain’s team willing him on, Ferrer capitalized on Del Potro’s errors as the Argentine followed up one of his 10 aces with his fifth double-fault to take it to a decisive set.
The fifth-ranked Ferrer carried the momentum and the support of the majority of the 26,000 spectators into the decider, and broke in the fourth and sixth games for a 5-1 lead.
Nadal returned to the comfort of clay after a disappointing performance at last week’s ATP World Tour Finals in London, and his best play followed as he broke Monaco seven times.
Monaco struggled to repel Nadal as the Spaniard converted the first of 14 break chances with a forehand passing shot for a 2-1 lead.
Nadal’s impressive selection of winners—he hit 26 in all—kept Monaco off-kilter during many long and remarkable rallies, including in the fourth game of the second set when Nadal curled a backhand down the line after repeatedly chasing down Monaco’s forehand.
“Sometimes you can hit two bad shots in a row and still steal the point,” said Nadal, who is 16-0 on clay in the competition. “That’s one of my best things on clay, while on hard indoor if I hit two bad shots in a row the point is done. Clay gives me a chance to play more relaxed.”
In the third set, the fifth game even drew King Juan Carlos out of his seat to applaud. Monaco fell into the net to give Nadal a break chance, and the Argentine was again in the clay after a lengthy exchange that closed with a Nadal smash at the net for 3-2. Monaco had his left wrist taped and carried a bloodied left knee after that and never got any closer.
“I felt like I was playing well but, frankly, it’s Rafa Nadal,” said Monaco, playing in his first final against one of his best friends. “Where can you win a point off this kid, is what you’re left wondering a lot of the time.
“From the very first moment he was solid, he always recovered his positioning. With any other player, the point ends much sooner. He didn’t give me any chances.”
Ferrer and Nadal are a combined 27-0 in Davis Cup matches on clay, a surface Spain hasn’t lost on for 22 ties, including a record 20 straight on home soil dating to 1999 as it vies for its third title in four years. It beat Argentina in 2008.