Former Manchester United player George Best was tonight continuing to battle for life as the doctor in charge of his care said: "We are not giving up".
Professor Roger Williams, who oversaw alcoholic Best's controversial liver transplant in 2002, said the 59-year-old had an unexplained bowel infection, which was causing complications to his treatment, but stressed he remained in a stable condition.
The former soccer star is in intensive care at the private Cromwell Hospital in London and is known to be suffering from internal bleeding.
He was admitted to the hospital nearly four weeks ago with an infection and his condition deteriorated when it spread.
Prof Williams said tonight: "His condition is stable but he does have a particularly nasty complication with bleeding from his bowel. "It is a complication that we don't fully understand, we don't know why this is happening and have, this afternoon, changed all of his antibiotics to try to get on top of it."
He said microbiologists had confirmed the infection was not linked to MRSA and added: "I can't say how serious the infection is and the bleeding comes and goes. "I have looked after him for a long time and we are not giving up."
Prof Williams confirmed Mr Best's son, Calum, had left the hospital after visiting this afternoon. He said that Best "still had every chance of pulling through this." He added: "The chances of that, I couldn't put a figure on it, it would be just a guess.
"He's a very tough fighter, he's been through many other crises." A spokesman for the hospital said: "He is in intensive care, and remains stable, as he has been all day. "He is on a ventilator, and his doctor has changed his medication today. The unit will be monitoring his response for the next 24 hours."
Best's agent Phil Hughes said on Wednesday night that the infection had spread from his chest to his kidneys and was also affecting other organs, adding his condition was "as bad as it gets".
Earlier today Prof Williams said the former footballer was being kept sedated while on the machine, but had been conscious when tests were carried out previously, and was "fully aware" of how serious the situation was. He said: "He wasn't in good spirits. He was very depressed, but is still fighting away, as he always does."