Madrid - Spain captain Sergi Bruguera said on Sunday that Rafael Nadal is "doing well" and wants to play at the inaugural Davis Cup Finals, despite his exertions at the ATP Finals this week.
Hosts Spain play their first tie against Russia in Madrid on Tuesday.
The 33-year-old Nadal was knocked out at the pool stage in London, but did secure the year-end world number one ranking ahead of Novak Djokovic.
Nadal was a fitness doubt for the season-ending event at the O2 Arena after pulling out of the Paris Masters with an abdominal injury, but managed to produce rousing comebacks in wins over Daniil Medvedev and Stefanos Tsitsipas.
"The truth is that he's in a great moment," said Bruguera on the eve of the tournament. "He is doing well and is eager to compete."
Five-time champions Spain have been handed a difficult draw in Group B with ties against reigning champions Croatia and Russia.
Bruguera said that Spain would not be favourites to progress from the group.
"On clay, I can't remember the last time Spain lost a Davis Cup tie," he said.
"But this (hard) surface is what we usually get when we play away from home. We find it more difficult."
Croatia will be led at the 18-team competition by former US Open champion Marin Cilic and Borna Coric, while Russia boast world No 17 Karen Khachanov and the in-form Andrey Rublev.
Nadal will receive support from Spanish number two Roberto Bautista Agut, Pablo Carreno Busta, Feliciano Lopez and Marcel Granollers.