Novak Djokovic (2nd L) of Serbia is comforted by team mates after his Davis Cup World Group semi-final match against Juan Martin Del Potro of Argentina in Belgrade, Sept 18, 2011. [Photo/Agencies]

PARIS - Rafael Nadal led Spain to a 4-1 Davis Cup victory over France on Sunday, and a final date with Argentina, but there were tears for US Open winner Novak Djokovic whose injury-forced retirement saw champion Serbia slump 3-2 to the South Americans.

As Nadal brushed aside fatigue from his US Open final loss to Djokovic, to win two of his side's semifinal rubbers, the tearful Serb collapsed on court in agony in Belgrade with back pain less than a week after his Flushing Meadows triumph.

Nadal slayed France's Jo-Wilfried Tsonga 6-0, 6-2, 6-4 in Cordoba's bullring to secure the winning point after the world No 2 thrashed Richard Gasquet 6-3, 6-0, 6-1 in Friday's opening rubber.

"It's really unbelieveable, the feelings are very, very emotional here today," said Nadal, who has a 18-1 win-loss record in Davis Cup and will compete in his sixth final.

"Today I felt good physically. Friday (against Gasquet) I wasn't quite there yet but because it wasn't a long match I could recharge my batteries for today."

Fernando Verdasco completed the rout for the host when he beat Gasquet 6-2, 6-1 in the final dead rubber.

In Belgrade, Djokovic admitted he had been carrying a back injury from the US Open as he retired while trailing 7-6 (5), 3-0 in the day's first reverse singles to Juan Martin Del Potro.

Djokovic, who missed the opening day's play, replaced Viktor Troicki in Sunday's lineup as captain Bogdan Obradovic tried to get the champion back into the tie in which it trailed 2-1 overnight.

"Of course I am very disappointed that the match ended this way," said the world No 1.

"I tried, but it did not work, I was not even 60 percent ready, but we have accepted that risk although we knew that my injury could worsen," said Djokovic, who had needed treatment on his back during his US Open final win.

It was only the third defeat in 67 matches this season for the Serb - two of them because of retirements.

Djokovic's absence on Friday had seen Serbia trail 2-0 before Troicki and Nenad Zimonjic defeated Juan Ignacio Chela and Juan Monaco 7-6 (4), 6-4, 6-2 on Saturday to keep the host's bid alive.

In the dead rubber, Monaco, who replaced David Nalbandian, retired after the first set against Janko Tipsarevic, which the Serbian player had won 6-2.

Argentina will travel to Spain for the Dec 2-4 final as it bids to win its first Davis Cup trophy after finishing runner-up in 1981, 2006 and 2008.

The Nadal-inspired Spanish, who are looking unbeatable on clay, are bidding for their fifth title after 2000, 2004, 2008, 2009.

David Ferrer defeated Gilles Simon 6-1, 6-4, 6-1 on Friday before Tsonga and Michael Llodra kept France's hopes alive on Saturday when they beat Feliciano Lopez and Fernando Verdasco 6-1, 6-2, 6-0.

In World Group playoff ties, the Czech Republic completed a 5-0 whitewash of Romania to advance along with Japan who beat India 4-1.

Russia, Austria, Italy, Croatia and Canada also booked their berths in next season's World Group.

Agence France-Presse