Argentina fought back to level an absorbing Davis Cup final against hosts Croatia in Zagreb as Juan Martin Del Potro beat Ivo Karlovic in four sets after Marin Cilic's five-set defeat of Federico Delbonis.
Neither world number six Cilic nor Argentine Del Potro were originally picked for tomorrow's doubles but both teams' talismans are now likely to be called upon for a potentially pivotal contest in what is shaping up to be a knife-edge tie.
Del Potro had to dig deep to overcome Karlovic, who was spurred on by an electrifying atmosphere in the Zagreb Arena.
A raucous home crowd was matched by an equally fervent Argentine contingent, which included the country's former football captain and World Cup winner Diego Maradona in the VIP box.
Del Potro broke Karlovic's serve early on and held his own to clinch the opening set but although the Argentine predictably dominated baseline exchanges, he was powerless against the Croatian's lethal serve.
Karlovic rifled in a flurry of aces to keep nosing ahead in the second set and saved a double break point to clinch the tiebreak, drawing wild cheers from the home fans.
That was as good as it got for the Croatian, however, as Del Potro upped the pace and prevailed in the last two sets, with an exuberant Maradona pumping his fists in delight.
Cilic had fired the hosts ahead by outlasting Delbonis 6-3 7-5 3-6 1-6 6-2 in a titanic tussle, having recovered after losing his momentum when he squandered three break points in the seventh game of the third set.
Cilic rained down a barrage of aces and service winners in the opening set after breaking his opponent's serve in the fourth game to edge ahead.
He broke again in the 11th game of the second set and held serve to take a commanding 2-0 lead before Delbonis hauled himself back into the match.
The Argentine saved three break points in the seventh game of the third set and claimed it with a searing forehand winner.
He could not miss in the fourth, racing through it with a barrage of spectacular shots against a subdued Cilic.
The resurgent Croatian found another gear in the fifth set, breaking Delbonis in the second game and again in the seventh before he sealed the match in three hours and 30 minutes.