Davis Cup - Nadal prepared to step aside
Nadal lost a gruelling US Open final to number one Novak Djokovic on Monday before flying straight back to Spain to join team-mates David Ferrer, Fernando Verdasco and Feliciano Lopez for the September 16-18 world group clash on clay in Cordoba.
"Here we are a team and, what's more, I would not play if the captain feels another team-mate is better prepared than me," Nadal said, insisting that he did not feel drained after losing his US Open crown to the in-form Serb.
"If I am not in shape, luckily Spain is still a force and there are top-level players.
"I have been competing at the highest level for three weeks, now there is a change of surface and that's something to assess. But luckily I am not physically drained."
Nadal has missed several Davis Cup ties through injury in recent years and the 25-year-old was absent for last year's 5-0 quarter-final loss to the French.
As hosts, Spain have chosen to play the tie on their favoured red dust and with Nadal playing and on form Costa's team would be firm favourites to advance to December's final, where they would meet champions Serbia or Argentina.
Spain and France have played each other seven times in the Davis Cup, with the Spaniards winning five. They are bidding for a third title in four years and a fifth overall.