Belgrade - Argentina beat champions Serbia 3-1 to advance to the Davis Cup final after US Open champion Novak Djokovic retired injured in the second set of his match against Martin Del Potro here on Sunday.
Del Potro was leading the world No 1 7-6 (7/5), 3-0 before Djokovic, visibly struggling to stay in the match, was forced to concede the game.
Djokovic, who missed the opening day's play with a back injury, replaced Viktor Troicki in Sunday's line-up as captain Bogdan Obradovic tried to get the defending champions back into the tie.
In Djokovic's absence Serbia had slumped 2-0 on Friday before Troicki and Nenad Zimonjic defeated Juan Ignacio Chela and Juan Monaco 7-6 (7/4), 6-4, 6-2 on Saturday to keep the hosts' bid alive.
Argentina will travel to Spain for December's final in a re-run of the 2008 final which the Spanish won in Mar del Plata.
Earlier Spain took an unassailable 3-1 lead over France in Cordoba.