World number three Andy Murray was forced to withdraw from the ATP World Tour finals here on Tuesday after failing to recover from a groin injury.
Murray was told he would need up to 10 days off after suffering the injury in practice last week and, although he initially ignored that advice to play David Ferrer in his opening match at the O2 Arena, he has now decided to pull out of the season finale less than 24 hours before he was due to face Tomas Berdych.
Murray, who will be replaced by Serbian Janko Tipsarevic, knew he was in trouble during Sunday's lacklustre defeat against Ferrer and he said: "It was one of those things where you kind of hope that things are going to get better, but reality was that wasn't ever going to happen.
"I woke up this morning still sore. I was just trying to find reasons why I should try to play.
"But there was no real positive of coming out and playing because on Sunday I was really unhappy on the court. I wasn't enjoying it at all.
"This is one of the best tournaments in the year, one that I think me and all of the players look forward to playing.
"I couldn't give anywhere near my best. So that's what was disappointing. It would probably do myself more damage by playing than not."
Murray tried to convince himself it was worth continuing but his lack of movement in practice was conclusive proof that it was too risky to play on.
The Scot admitted his main concern was to avoid damaging the groin further before he goes to America to begin his off-season conditioning regime ahead of the Australian Open in January.
"I was told a week to 10 days of total rest. I just didn't have enough time to recover," he said.
"Each day I was hitting up and down the middle of the court, not moving. I went to do some serve movement work to test it out and I had to stop when I was doing that.
"Then on Sunday I played some points with Tipsarevic and I didn't feel good. I stopped the practice early.
"I was just disappointed because I knew in my head I wasn't ready to play and wasn't right to play.
"I never want to pull out of tournaments, especially one of this size. But it's a decision I kind of had to make because I was probably going to do myself more damage.
"It might seem like it's a long time away but the Australian Open is six, seven weeks away.
"I could mess up my preparation for that, for the beginning of the year. That off-season is so important for me and has been for the last few years of getting myself in shape.
"It's one of the few times when you can have an actual training block."
After pushing himself through a gruelling tour of Asia that included tournament wins in Bangkok, Tokyo and Shanghai, Murray conceded that the strain on his body might have been too much.
He pulled out of the recent Basel event to try to rest his aching limbs but in hindsight he believes he might have been better taking a longer break.
"Right now it doesn't feel great. But more so because it's the end of the year," Murray added.
"Because of the event that it is, you kind of want to go out having almost given everything and there's no chance I would have been ready to win the tournament here.
"So in hindsight it was maybe the wrong decision. If you look at the other guys that played loads of matches this year, Roger and Novak both took a large break after the US Open.
"Rafa took one after Asia. Maybe me trying to get ready for Basel was too soon. That's something I probably need to learn from because I had played a lot of matches."