World number three Andy Murray has pulled out of the ATP World Tour Finals with a groin injury.
The British number one, who strained the muscle in training Nov 14 had a recurrence in Monday's defeat at the hands of David Ferrer of Spain at London's O2 Arena.
"I was told to take a week to 10 days completely off, I just didn't have enough time to recover," BBC quoted the disappointed Scot as saying.
"I was probably going to do myself more damage playing than not."
Murray was to practise at 1300 GMT (6.30 IST) Tuesday, but he failed to turn up and instead a hurriedly convened press conference saw the Scot announce his decision to pull out. He has been replaced by world number nine Janko Tipsarevic of Serbia.
"When I came off the court (Monday), I was very disappointed and upset," said the 24-year-old Murray.
"I said we'd see how I feel when I woke today up but I was never going to feel great. You hope things are going to get better, but in reality that wasn't ever going to happen.
"I woke up this morning still sore, came in and was going to hit. We chatted for about two hours - about when I was going to be practising, what I should do, what the right thing to do was."
"I had some food, we spoke more about it. 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 yesterday I was really unhappy on the court. I wasn't enjoying it at all."
Murray will return to action at the Brisbane International which begins New Year's Day.
The Australian Open, the first Grand Slam of the year, follows Jan 16.
Tipsarevic, who has a narrow lead over Nicolas Almagro in the rankings to secure his spot as first reserve for the tournament, said he had expected to play here.