BARCELONA, Spain -- Rafael Nadal will miss Spain's Davis Cup final against Argentina because of a knee injury.
The top-ranked Nadal said Monday he was still struggling with tendinitis in his right knee following a week of treatment.
"The knee said no," the 22-year-old said.
Spain team doctor Angel Ruiz-Cotorro said Nadal would need three to six weeks to recover from the injury.
"These are very difficult moments, but I have done all that I could to be ready for the final," he said. "It was a huge objective, and I'm used to playing with pain, but this is a distinct, new pain that I couldn't control."
Nadal's absence deals a big blow to Spain's bid for a third Davis Cup title since 2000. Spain captain Emilio Sanchez Vicario has until Tuesday to name his team.
Spain plays Argentina on indoor hard court at Mar del Plata from Nov. 21-23.
"We're sorry for him, but it's good news. Spain is one thing with Nadal and another thing without him," Argentine captain Alberto Mancini told Buenos Aires-based radio station Continental.
Nadal was a key player when Spain beat the United States 4-1 in the semifinals, winning both his singles matches.
Sanchez Vicario will most likely replace Nadal with Tommy Robredo, clay-court specialist Nicolas Almagro or Marcel Granollers. David Ferrer, Feliciano Lopez and Fernando Verdasco are expected to be back on the team.
Nadal this year won a fourth straight French Open and his first Wimbledon title. He withdrew from the Paris Masters last month with an injury to the same knee after losing the first set of his quarterfinal against Nikolai Davydenko. He then pulled out of this week's season-ending Masters Cup in Shanghai, China.
Nadal also won the Olympic gold medal in a year when he supplanted Roger Federer at No. 1.
"I don't know if the injury [resulted] from my fight to be No. 1 because in reality, I didn't play in any extra tournaments, I only played what I had to for the ranking and I don't think you can reproach me for that," Nadal said. "I didn't do anything crazy to be No. 1."
Ruiz-Cotorro said the injury was not career-threatening but that it was "totally impossible" for Nadal to be ready in time for the final.
"Rafa comes in off a very tough year and his body has been warning him for weeks. It's an acute injury that needs time to recuperate," Ruiz-Cotorro said. "If he played in Argentina, it could become worse."
Robredo helped Spain to a 5-0 rout of Peru in a first-round match in February but has reached the quarterfinals of only one of nine tournaments since winning at Bastad in July. The 21st-ranked Robredo has been a Spain regular since 2004.
The 19th-ranked Almagro made his debut against Peru, winning both singles matches, while 56th-ranked Granollers has never been selected.
"Spain has top-level players capable of achieving victory," said Nadal, who didn't rule out traveling to South America to support his teammates.