Novak Okokovic revealed he was in severe elbow pain but refused to blame him for defeating Roger Federer in the ATP final.
Okokovic suffered a problem with the US Open elbow in September, but recovered to win in Tokyo and Paris before arriving at the season tournament.
In the last match of the Bjorn Borg Group, okokovic faced a shootout with Federer to reach the semifinals.
But in the first set, the 16-time Grand Slam champion singled out Federer, who produced a service master class.
Federer then broke Okokovic in the early stages of the second set and sealed the victory by piercing the 32-year-old player for the third time.
During the second set, okokovic was caught stretching and rubbing his elbow.
And in his post-match press conference, he told reporters that the issue was repeated again.
He said: "Yes, well, I hope there is nothing I can really do to play Madrid. You know, the pain was pretty sharp.
"But I could play the rest of the game, so, you know, if I had something really serious, I think I wouldn't be able to keep the rocket.
"So it was probably a tricky, fast-moving. It was not a form of questioning later. "
Djokovic is scheduled to represent Serbia at the Davis Cup next week and he said he hopes he can still play.
He said, "Well, I hope. You know, things are good now physically.
"Sure, the gas tank is not as full as the season started, but I'm motivated to join the guys and play there, because I haven't played in the Davis Cup team for a while.
"That's why I look forward to it. They are my dear friends, all the guys on the team and I can't wait to feel that team spirit. The format is different. It should be exciting."