Rafael Nadal reacts after beating Argentina's Juan Martin del Potro 1-6, 6-4, 6-1, 7-6(0) and win the Davis Cup for Spain 3-1 in Sevilla on Sunday.

Spain's Davis Cup future was clouded by uncertainty yesterday after world No. 2 Rafael Nadal announced he would not be available next year and captain Albert Costa said he needed time to think about whether to stay on.

The Iberian nation secured its fifth title and a third in four years by beating Argentina on Sunday, Nadal winning the decisive point in a thrilling match against Juan Martin del Potro on the clay at Seville's Olympic Stadium.

The 25-year-old Mallorcan has repeatedly complained about what he sees as an overloaded ATP World Tour calendar and told a news conference the added burden of competing in the 2012 Olympics in London, where he will bid for a second consecutive singles gold, meant Davis Cup participation was impossible.

Costa, a former French Open singles champion who has led Spain to two titles in his three-year stint at the helm, said he would take a week off to think about his future.

"We still have what it takes to keep fighting for the title but the reality is that I have doubts about what is going to happen now to the national team," Manolo Santana, a Spanish former French Open, Wimbledon and US Open champion, wrote in yesterday's El Mundo newspaper.

With talisman Nadal, who has won 20 of his 21 Davis Cup singles rubbers, stepping aside, Spain is still likely to be able to count on world No. 5 David Ferrer and doubles pair Feliciano Lopez and Fernando Verdasco in 2012.

It also has a number of experienced players waiting in the wings including 10th-ranked Nicolas Almagro, who won three Tour singles titles this year, and No. 27 Marcel Granollers, who won two.

Adding to the uncertainty, however, is the poor form of Lopez and Verdasco, who has been the weak link in Spain's recent David Cup outings.

The pair suffered a drubbing at the hands of French duo Jo-Wilfried Tsonga and Michael Llodra in the semifinals before being trounced by Argentina's David Nalbandian and Eduardo Schwank in the final.

"It seems clear that in the doubles we are going to have to experiment with another pair," Santana wrote.

Emilio Sanchez-Vicario, who captained Spain to victory over Argentina in the 2008 final in Mar del Plata, said Spain needed new faces and an injection of fresh energy.

Bringing the 26-year-old Almagro and Granollers, 25, into the side would keep Spain competitive for the next few years, he wrote in El Mundo.