The United States stayed alive 1-2 on Saturday as the ad hoc doubles pairing of Mike Bryan and Mardy Fish rallied for a desperation 4-6, 6-4, 6-3, 4-6, 6-4 victory over Fernando Verdasco and Feliciano Lopez in the Davis Cup semi-finals, reported dpa.
Russia did the same, recovering from 0-2 down thanks to a doubles victory from Dmitry Tursunov and Igor Kunitsyn, which kept their nation in the weekend chase 6-2, 6-1, 6-7 (9-11), 3-6, 8-6 over David Nalbandian and Guillermo Canas in Buenos Aires.
Spain and Argentina each still stand one reverse singles win away on Sunday from lining up in the November title match, with the Spanish seeking a second final since 2004.
In South America, the Argentines saved three straight match points in the third set but proved unable to close the gap in the end.
In Spain, Bryan and late substitute Fish kept visiting hopes alive with the victory in just over three hours. It was the first time Bryan played with someone other than his injured twin brother Bob in the Davis Cup since 2003.
"The key to this match was us bonding," said Fish. "We've been great friends for years and you play your best tennis when you are having fun."
Added the experienced Byran: "I admire the way Mardy played today, It was a hard fought battle. We took our chances when we got them but it took a little while to get going."
The defending champion Americans clawed back to stay in the weekend chase, breaking to start the fifth set.
"It was very close, the toughest thing was to come back from two sets to one down and a break," said Lopez. "With a bit more luck we could have won. The crowd helped us a lot in the fourth set."
Spain are looking for their first final in the worldwide team competition since beating the Americans in Seville four years ago.
Rafael Nadal and Davis Ferrer had assured the hosts of the opening day singles on Friday as both posted wins in more than three hours on a court set up inside a Madrid bullring.
Nadal stopped Sam Querrey, while Ferrer pulled out a last-gasp win over Andy Roddick to end a nine-match win streak for the top American.
The Spaniards are aiming for their 14th successive winning tie at home and 16th straight on clay.
Fish, to be married next weekend to a television model, was drafted into the field after a shoulder injury kept Bob Bryan away.
Lopez and Verdasco failed to break on 10 opportunities, with Bryan and Fish staging a comeback after losing the first set.