Formula One legend Michael Schumacher's condition has shown slight improvement after a second operation, but he is not out of danger, doctors at the hospital in Grenoble, where he is being treated, said on Tuesday.
The operation to reduce swelling on his brain took around two hours and was carried out at 10pm on Monday, doctors said. They said a scan taken following the operation revealed a slight improvement.
"We are surprised by the improvement," one doctor said at a press conference, adding that the medical team had "gained some time". Schumacher has been in a medically-induced coma after an off-piste skiing accident near Méribel in the French Alps on Sunday.
Doctors warned, however, that it was still touch-and-go for the German racing legend as they wait for the full extent of his injuries to become clear after he fell and slammed his head on a rock while skiing off-piste near the upmarket resort of Méribel.
He is still in a "critical condition" and is "fragile", one doctor told reporters at the press conference on Tuesday.
Doctors say his family, who are by his side, took the "difficult decision" to go ahead with the second operation, when an opportunity emerged. Doctors will continue their "hour by hour" treatment to try to oxygenate his brain and reduce swelling.
Jean-Francois Payen, head of the intensive care unit, told reporters at a press conference on Tuesday that Schumacher was still in danger.
"We cannot speculate on the future," he said.
Schumacher had been placed in an artificial coma to limit the impact of his head injuries on his brain.
Doctors at the hospital in the southeastern city of Grenoble where Schumacher is being treated said on Monday their famous patient was fighting for his life, but said it was too early to say whether Schumacher, who is due to turn 45 on January 3rd, would pull through.
"It usually takes 48 hours, or even longer, to be able to formulate an opinion" on injuries of this severity, said neurologist Jean-Luc Truelle on Monday.
The coma reduces the patient's temperature to around 35 degrees Celsius (95 degrees Fahrenheit) to reduce swelling. By being unconscious, the brain is also switched off to sounds, light and other triggers that cause the organ to use up oxygen as it processes the stimuli.
Investigators in the upmarket Méribel resort where Schumacher was staying have opened an investigation into the circumstances of his fall.
Schumacher was skiing off-piste with his son, when he hit his head on rocks buried just beneath 40 cm of fresh snow.
Schumacher and his son, however, were not far off the main ski run, with some suggesting he may have just been trying to take a short cut between two runs rather than actually adventuring off-piste. Investigators do not believe a third party was involved in the accident.
There has been less snow than usual in Méribel this year and strong winds have reportedly blown fresh snow away from the usual runs, making life more difficult for skiers.
Schumacher's condition was initially described as non-life-threatening after he was helicoptered off the mountain.
However it quickly deteriorated and he fell into a coma.
Stephan Chabardes, who operated on Schumacher, said the former racer arrived in hospital on Sunday in an agitated state - his arms and legs jerking uncontrollably - and was not able to answer questions.