London: Rafael Nadal pulled out of the ATP Finals, admitting he had lost his fitness battle after crashing to defeat in three sets to David Goffin in a thrilling encounter.
The world number one dug deep but was stunned 7-6 (7/5), 6-7 (4/7), 6-4 by Goffin in his opening match of the end-of- season finale, which he has never won in his illustrious career.
The Spaniard came into the tournament with doubts swirling over his fitness after pulling out of the Paris Masters with a knee injury.
Initially he showed no obvious ill-effects during a rollercoaster round-robin encounter in front of a supportive crowd but eventually his injury caught up with him and forced him to admit his season is over.
"No, I am off," said Nadal. "My season is finished. Yeah, I had the commitment with the event, with the city, with myself. I tried hard. I did the thing that I had to do to try to be ready to play. But I am really not ready to play."
"Is about the pain," he added. "I cannot hold with enough power to keep playing. I tried, but seriously it was a miracle to be very close in the score during the match. It really doesn't make sense."
Nadal said he would work hard to be ready for the start of the next season.
"I know what I have to do," he said. "I know all the things that happened in the past when I had these things, and I know the treatment that I had to do. I know the periods of time that I need to work. Then if the treatment works or not, we will see."
Nadal, 31, struggled to find his range early in front of a raucous crowd rooting for him and was broken twice in the first set by the Belgian seventh seed, who had lost their previous two encounters.
The Spaniard appeared to have earned a psychological edge when Goffin double-faulted while serving for the set and the match went into a tie-break but the Belgian re-found his focus to come out on top.