Andy Murray called a premature end to his 2011 season in London this afternoon to ensure he does not compromise his chances in 2012.
The world number three revealed after yesterday's straight-sets defeat by David Ferrer at the O2 Arena that he was considering pulling out of the Barclays ATP World Tour Finals with a left groin strain.
The signs did not look good when he failed to show for a scheduled practice session at 1pm and he announced at a press conference late this afternoon that he had indeed made the difficult decision to withdraw.
Murray had kept the injury, which he suffered in practice last Monday, quiet prior to the tournament but he confirmed today he had been told to rest completely for up to 10 days.
He chose not to withdraw at that stage but, after a two-hour discussion with his team today, he decided the risk of further injury was simply too great.
The Scot said: "I came off the court yesterday and I was very disappointed.
"I was never going to feel great today. It was one of those things where you kind of hope that things are going to get better, but the reality was that wasn't ever going to happen.
"We chatted for about two hours, when I was going to be practising, about what I should do. I was just trying to find reasons why I should try to play.
"But there was no real positive to coming out and playing because yesterday 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. I would probably do myself more damage by playing than not."
Murray is no stranger to playing through niggles and he is renowned as someone who only pulls out of tournaments as a last resort.
The last time he withdrew midway through an event was in Dubai nearly three years ago while his only retirement during a match came in Hamburg in 2007 when he snapped a tendon in his wrist.
Murray compared the situation to this year's French Open campaign, when he twisted an ankle in the third round but battled on and eventually reached the semi-finals.
He said: "(In Paris) I was able to play a match and win a match and get through it when I did it. This time I did it one week before the tournament. I was told (to take) a week to 10 days off of total rest. I just didn't have enough time to recover.
"The Australian Open is 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 for getting myself in shape."
Murray had been one of the favourites to win the title prior to the tournament because of his superb form this autumn, which carried him to back-to-back titles in Bangkok, Tokyo and Shanghai.
The 24-year-old conceded he probably should have pulled out before the tournament, saying: "I knew in my head I wasn't ready to play and wasn't right to play.
"I want to come into the big competitions being there to win the event, and there's no chance I would have been ready to win the tournament here. So, in hindsight, it was maybe the wrong decision, but you want to try and give yourself an opportunity if you can."
Murray's place in Group A will be taken by world number nine Janko Tipsarevic, who enters the fray still with a chance of making the semi-finals, although he will probably need to beat Tomas Berdych tomorrow and fellow Serb Novak Djokovic on Friday.