Ironman David Ferrer beat Juan Martin del Potro 6-2, 6-7 (2/7), 3-6, 6-4, 6-3 on Friday to hand Spain a 2-0 lead over Argentina in the Davis Cup final and inch them closer to a fifth title.
Ferrer needed four hours and 44 minutes to see off the battling del Potro after Rafael Nadal had earlier cruised to his 19th win in 20 rubbers in the competition with a 6-1, 6-1, 6-2 win over close friend Juan Monaco.
Spain can wrap up the title if Fernando Verdasco and Feliciano Lopez see off David Nalbandian and Eduardo Schwank in Saturday's doubles, which would leave Argentina still searching for a first Davis Cup crown.
"I played the best match of my career," said Ferrer.
The Spanish number two, who made the semi-finals at the ATP World Tour Finals last week in London, had looked down and out against a free-hitting del Potro in the second and third sets in front of a raucous 28,000-strong crowd at the Estadio Olimpico.
But the big Argentine gradually wilted, slipping 5-1 down in the decider.
He managed to retrieve a break and hold to put the pressure back on Ferrer, but the Spaniard held his nerve to wrap up the rubber with a sweeping winner.
"He's David Ferrer, he fights all the time," said Spain captain Albert Costa.
Sadly for Argentina, history will not be on their side on Saturday -- the last team to recover from a 2-0 deficit in the final was Australia in 1939.
"We saw tonight that even playing incredible tennis you can still lose to Spain," said an emotional del Potro.
"But we still have a chance. I have confidence in David (Nalbandian) and Eduardo (Schwank). We are still alive."
Nadal may be suffering from mental and physical tiredness at the end of a gruelling season, but he repaid the faith shown in him by Costa by winning in less than two and a half hours to maintain Spain's 12-year unbeaten home record in the Davis Cup.
It was the Mallorcan's 67th best-of-five-sets match on clay, and his 66th win, with his sole defeat coming at the hands of Robin Soderling at Roland Garros in 2009.
He was far too strong for his 26th-ranked opponent, returning superbly and not facing a single break point over the course of the match.
"I played a very solid match and I am very happy with my performance," said Nadal after his 19th win in 20 singles rubbers for Spain.
His only loss came to Czech Jiri Novak on his debut -- as a 17-year-old -- in February 2004. He is 15-0 in clay-court rubbers.
"I was very positive before the match even if there was a lot of pressure. It's an important victory. To win by such a score against a very strong player on clay is fabulous. I was sad for him as he is one of my best friends," said Nadal, who also praised the crowd.
"I love playing at home. The atmosphere is great, it's like a football match."
Monaco saved three break points in the very first game, but was soon swept away by the six-time French Open champion.
Nadal sent down 27 winners to Monaco's 17, while the Argentine was undone by 35 unforced errors. The former world number one also won seven of 14 break points.