Spain went 2-1 ahead in the Davis Cup final against Argentina on Saturday when Fernando Verdasco and Feliciano Lopez beat David Nalbandian and Agustin Calleri in a fiery doubles encounter.
Nalbandian and Calleri took the first set before the visitors hit back for a 5-7, 7-5, 7-6 (7-5), 6-3 win in three hours 19 minutes to put Spain within reach of a shock win.
Argentina, who have won their last 13 home ties in a run stretching back 10 years, started as favourites against a Spain team missing injured world number one Rafael Nadal.
But captain Alberto Mancini said the hosts are feeling the heat as they attempt to win the competition for the first time.
"The boys are under a lot of pressure and it's not easy to deal with," he said.
"All the matches have been very even. I think we had a little bit of bad luck."
The match hinged on a dramatic third set where Spain raced to a 5-1 lead but Argentina hit back to force a tiebreak.
The hosts then led 5-1 in the tiebreak before the Spanish won six points in a row to take the set.
"It was tough to go 5-1 up and then go to a tiebreak, it was tough mentally but that was the key," said Verdasco. "After that we played better and much looser."
Spain coach Emilio Sanchez Vicario said his pair were more together than Calleri and Nalbandian, whose last Davis Cup match together was two years ago in the final against Russia.
"This made the difference," he said. "They were more united, they helped each other, when one was down the other picked him up."
Argentina took the first set after Verdasco dropped his serve in the 11th game, the Spaniard appearing to be distracted by hissing in the crowd.
But Verdasco found his confidence in the second and the Argentine pair struggled with his powerful shots from the baseline.
The second set went with serve until the 12th game when Nalbandian was broken following two mistakes by Calleri, who sent a smash into the net and over-hit a volley in successive points to hand Spain the set.
The third set was a see-saw affair as Spain raced to a 5-1 lead, Nalbandian losing another serve in the process.
Argentina saved a set point in the seventh game then went on to break Verdasco's serve helped by a delightful lob by Nalbandian and a double fault from the Spaniard.
That revitalised the hosts and they hit back to level 5-5 and send the set to a tiebreak
With the crowd in full voice, Argentina raced to a 5-1 lead in the tiebreak only to lose concentration after Calleri was distracted by a fan as he was about to serve.
Both sets of players appealed for calm as match officials lost control of the situation and when play re-started, Spain reeled off four points in a row.
Lopez then gave Spain set point with a superb lob from the baseline before the error-prone Calleri hit a service return into the net.
Spain took advantage of an increasingly error-prone Calleri to break service twice in a row in the fourth set and wrap up the match.
The Spanish need to win one of Sunday's two singles matches to clinch the title for the first time since 2004.