Novak Djokovic has revealed his sharp pain in his elbow but refuses to blame him for his defeat to Roger Federer in the ATP Final.
Djokovic suffered elbow problems at the US Open in September but has recovered from that to win in Tokyo and Paris before arriving at the end of season tournament.
In Bjorn Borg's final group match, Djokovic faced a shootout with Federer to reach the semi-finals.
But in the first set, the 16-time Grand Slam champion lost to Federer, who produced a master class.
Federer then broke Djokovic in the early stages of the second set and sealed the victory by breaking the 32-year-old's serve for the third time.
During the second set, Djokovic was caught stretching and rubbing his elbows.
And in his post-match press conference, he told reporters that the problem did indeed recur.
He said: "Yes, well, I hope nothing really makes me unable to play Madrid. You know, the pain is quite sharp.
"But I can play the rest of the match, so, you know, if I have something very serious, I don't think I can hold a racket.
"So it might just be a quick and awkward move that I do. It doesn't cause any problems later on."
Djokovic is scheduled to represent Serbia in the Davis Cup next week and he said he hoped he could still play.
He said: "Well, I hope. You know, the physical condition is fine now.
"Of course, the gas tank isn't full at the start of the season, but I was motivated to join the players and play there, because I haven't played in the Davis Cup team competition for some time.
"So I look forward to it. They are my dear friends, everyone on the team, and I can't wait to feel the team's spirit. The format is different. It should be interesting."