Fabio Fognini rallied to beat Guido Pella 2-6, 4-6, 6-3, 6-4, 6-2, giving Italy a 3-2 win over host and defending champion Argentina in a first-round Davis Cup tie here.
"I am happy because I put everything I had. I played very badly at the beginning, I waited until the end to find my game and now I feel great joy for this triumph," Fognini said, reports Efe.
Fognini, the world no 48, dug in against world no 84 Pella in the third set on clay at Parque Sarmiento, capitalising on mistakes by the Argentine who blew two break opportunities.
The match, rescheduled due to rain, strong winds and darkness on Sunday, was not free of the usual antics from the volatile Fognini.
He received a warning for unsportsmanlike conduct after he smashed his racket into the ground in the second set.
Fognini argued with fans in the stands and the chair umpire during the first two sets and he kicked a wall at one point to vent.
Pella, however, was unable to put the Italian away and the frustration got to him in the fourth set when he smashed his own racket after blowing two break chances in the sixth game.
Argentina was without Juan Martin del Potro, the hero of the South American nation's maiden Davis Cup triumph last year.
The 28-year-old del Potro has battled numerous wrist injuries in recent years and concerns about his long-term health led him to skip both last month's Australian Open and the first-round Davis Cup tie.
Italy will travel to Belgium to play in the quarterfinals of tennis' premier international team event.