Formula One legend Michael Schumacher on Tuesday showed a slight improvement after a second operation following his life-threatening ski accident but was "not out of danger," doctors treating him said.
Surgeons said they had "gained some time" by performing a successful second procedure on the seven times world champion on Monday night but he still remained critical.
His wife and two children are at the hospital in the French Alpine city of Grenoble where the former racing driver remains in a coma after he fell and slammed his head on a rock while skiing off-piste on Sunday.
News of the accident stunned the world and racing stars joined German Chancellor Angela Merkel and legions of fans in expressing their hopes for his recovery.
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Schumacher underwent an operation soon after being helicoptered to the hospital on Sunday, and surgeons performed the second nearly two-hour-long procedure to remove bleeding in the left side of the brain.
Jean-Francois Payen, head of the intensive care unit, warned reporters during a press conference on Tuesday morning that Schumacher was not out of the woods.
"We cannot speculate on the future," he said. "We cannot say he is out of danger but we have gained some time."
He said scans showed that the removal of the bleeding had been done in a "satisfactory manner", but ruled out Schumacher's transfer from the hospital as it could be "dangerous."
A file photo of Michael Schumacher during the first practice of the F1 San Marino GP race in Italy. (AFP photo)
Emmanuel Gay, head of the neurosurgery department, said he was "surprised" by the improvement in Schumacher's condition.
Doctors have said that Schumacher, who is due to turn 45 on January 3, has age and physical fitness on his side.
He had been put in a medically induced coma to spur recovery. His temperature has also been reduced 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.
Helmet smashed 'in two'
A source close to the investigation into the off-piste accident at the upmarket ski resort of Meribel told AFP that Schumacher's helmet, which medics say saved his life, was smashed "in two" by the impact.
The German newspaper Bild also quoted a rescuer as saying the split helmet was "full of blood".
Schumacher's family in a statement expressed their thanks to the doctors who they said were doing "everything possible to help Michael" and to well-wishers around the world.
Damon Hill, who fought several memorable on-track battles with Schumacher, said he was "praying" for his former rival.
A file photo of Schumacher at the end of the Brazil's GP in Sao Paulo. (AFP photo)
Merkel was "extremely shocked" by the incident, her spokesman Steffen Seibert told reporters.
Formula One quadruple world champion Sebastian Vettel, 26, who has said Schumacher was his childhood idol, said: "I am shocked and I hope that he'll be feeling better as soon as possible.
Schumacher, who won the last of his world titles in 2004, towered over the sport since his debut in 1991, winning more Formula One world titles and races than any other. He had a record 91 wins and is one of only two men to reach 300 grands prix.
His duels in his heyday with Hill and Jacques Villeneuve, fired by an unquenchable competitive spirit, have gone down in Formula One lore.
Schumacher was born in January 1969 near Cologne, Germany, the son of a bricklayer who also ran the local go-kart track, where his mother worked in the canteen.
By 1987, Schumacher was the German and European go-kart champion and was soon racing professionally. In 1991 he burst into Formula One by qualifying seventh in his debut race in Belgium and a year later, he won his first Formula One grand prix.
He joined Ferrari in 1996 and went from strength to strength over the next decade, dominating the podium, before retiring aged 37.
But the father of two could not resist the lure of the track and in 2010 he came out of retirement, signing a deal with Mercedes before quitting for good in 2012.