Tomas Berdych recovered from two sets to one down, and 1-4 behind in the fourth set, to stun Juan Monaco 6-1, 4-6, 1-6, 6-4, 6-4 and pull the Czech Republic level 1-1 with Argentina in the Davis Cup semi-finals Friday.
With Argentine football legend Diego Maradona and former tennis glamour girl Gabriela Sabatini amongst the raucous 13,00-crowd inside Parque Roca, Berdych dug deep to claim a famous win for the Czechs.
Berdych, who defeated Roger Federer on his way to the US Open semi-finals last week, won nine straight games to lead 5-3 in the decider.
But Monaco stopped the rot for a break to trail 4-5 before Berdych broke again to seal victory.
Earlier, Juan Martin del Potro got Argentina off to a winning start with victory in straight sets against Radek Stepanek.
Del Potro, ranked eighth in the world, needed two hours and 41 minutes to beat Stepanek 6-4, 6-4, 6-2 on the clay of Parque Roca.
Argentina will now look to their doubles pairing of Carlos Berlocq and Eduardo Schwank, who face Berdych and Stepanek, to restore their advantage on Saturday.
Argentina have never won the Davis Cup, falling in the final in 1981, 2006, 2008 and 2011.
The Czechs were champions in 1980 and reached the final in 2009 where they were defeated by Spain.
The winner of this tie will go through to the final against holders Spain or the United States, who are meeting in the other semi in Gijon this weekend.
Spain were leading 2-0 at the end of the first day.