Czech star Tomas Berdych battled back to defeat Juan Monaco in five sets and level their Davis Cup semi-final against Argentina at Parque Roca.
In a marathon encounter US Open semi-finalist Berdych came through 6-1 4-6 1-6 6-4 6-4 in just over four hours of gruelling action.
The world number six was quickest out of the blocks, comfortably taking the first set.
His opponent soon found his feet though in front of a passionate home crowd which included football legend Diego Maradona, as he took the next two sets.
Monaco then found himself a break up in the fourth set and seemingly on the way to a comfortable victory.
However, Berdych broke back and then won the next three games to take the set 6-4 and then edged the decider to leave the scoreline 1-1 after the first day.
In the first rubber, Juan Martin del Potro showed few signs of being slowed by an injured left wrist as he put Argentina 1-0 up.
The world number eight, who was told by doctors not to play with the inflamed wrist, produced a masterclass as he defeated Radek Stepanek 6-4 6-4 6-2 in their singles match.
Del Potro broke the Czech in the ninth game at the clay-court venue en route to winning the first set.
As the match wore on, the Argentinian got stronger and stronger, breaking Stepanek twice in the second and third sets as he cruised to victory.
The 2009 US Open champion broke down in tears as he spoke to the crowd afterward on a courtside microphone.
"You can see how I suffered playing. I did it for all of you," said an emotional Del Potro.
"Playing here means so much for you, for the country, for Argentine tennis for everyone and me too. I want to thank you for the love and support you have always shown me"
Argentina are attempting to reach their fifth Davis Cup final. They have lost all four previous finals, including defeat to Spain last year.