Murray admitted defeat after waking up sore yesterday morning, having aggravated a groin injury during his straight-sets defeat to Spain’s David Ferrer in his opening match at the O2 on Monday.
The Scot (inset) had been due to play his second match of the group stage this afternoon, but felt he had little choice but to withdraw or risk a longer lay-off and jeopardise his chances of winning an elusive first grand slam in January.
“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,” said Murray.
“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. That off-season is so important for me and has been for the last few years of getting myself in shape.”
Murray, whose place will be taken by Serb Janko Tipsarevic, was told to take 10 days off last week when he sustained the injury, and conceded he should probably have never begun the season-ending tournament.
“You hope that things are going to get better, but the reality was that wasn’t ever going to happen,” the world No3 added.
“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. I would probably do myself more damage by playing.”
Murray, who last pulled out mid-tournament in 2008, also struggled with injury at the Paris Masters earlier this month.
Before that he had been in stellar form, winning three consecutive hard court competitions in Bangkok, Tokyo and Shanghai.