Teenager Juan Martin del Potro, making his Davis Cup home debut, demolished a listless Nikolay Davydenko to put Argentina 2-0 ahead in their semi-final against Russia on Friday.
David Nalbandian drew first blood for Argentina with a straight sets win over Igor Andreev before Del Potro, 19, strolled onto the court for a 6-1, 6-4, 6-2 win over the world number six.
Argentina will reach the final, which starts on November 21, by winning Saturday's doubles with Agustin Calleri and Guillermo Canas due to play Igor Kunitsyn and Dmitry Tursunov.
Spain lead the United States 2-0 in the other semi-final after Friday's singles rubbers in Madrid.
Davydenko, who said during the Olympic Games he had lost his appetite for the game, made it easy for Del Potro by committing 34 unforced errors.
Del Potro, helped by a rowdy crowd at the Parque Roca, broke in the fourth and sixth games to wrap up the first set in 32 minutes.
Davydenko interspersed his mistakes with the odd winner in the second set, saving five set points, but eventually succumbed.
Del Potro began the third set with another break, which he repeated in the fifth game, and wrapped up the rubber when Davydenko sent a service return into the net.
"I can't think of anything to say," said Del Potro, who shot to prominence by winning four ATP tournaments in a row this year.
Nalbandian needed 2-1/2 hours for his 7-6, 6-2, 6-4 win, which hinged on a controversial line call in the first set tiebreak.
With Andreev leading 4-2, Nalbandian had a forehand called out but the umpire overruled the decision and ordered that the point should be replayed.
Frustrated by this, and possibly unnerved by the crowd shouting and whistling as he served, Andreev made three unforced errors before Nalbandian wrapped up the set with a volley at the net.
Nalbandian carried the momentum through into the next set, producing the first service break of the match in the fourth game.
Andreev had two points to break back in the seventh but blew his chance with another flurry of unforced errors.
The third set went with serve until the final game when Nalbandian produced a pinpoint backhand down the line to give him two set points.
The Russian saved the first but on the second sent his backhand into the net to give Argentina a 1-0 lead.
"It was a good game for me, he's a good opponent especially on clay," said Nalbandian. "It's a great motivation to play in Argentina with this spectacular crowd."
"It's been much easier than we expected," said Argentina team captain Alberto Mancini.