Formula One legend Michael Schumacher remained “stable” but was still in a critical condition on Thursday after four nights in hospital battling severe brain injuries following a skiing accident in France.

The German racing great remained in an induced coma and a critical condition, with his wife Corinna, 16-year-old daughter Gina-Maria and 14-year-old son Mick at his bedside in the French Alpine city of Grenoble.

The seven-time world champion’s fight for survival after he fell and slammed his head on a rock Sunday has shocked legions of fans used to seeing him cheat death on the racing tracks.

“At the moment, he is stable,” the 44-year-old’s manager Sabine Kehm told reporters massed outside the hospital in Grenoble on Wednesday.

Schumacher was helicoptered off the slopes at the upmarket Meribel resort on Sunday and it quickly emerged he was fighting for his life as doctors reported he had undergone emergency brain surgery.

On Tuesday, they said a slight improvement in his condition had allowed them to perform a second nearly two-hour long procedure to remove bleeding in the brain, but warned he was “not out of danger” yet.

“We cannot speculate on the future,” said Jean-Francois Payen, head of the intensive care unit at the hospital.

“We cannot say he is out of danger but we have gained some time.”

Doctors have pointed out that Schumacher, due to turn 45 on January 3, has age and physical fitness on his side.

He has been put in a medically induced coma to spur recovery, and his temperature has been reduced to around 35 degrees Celsius to reduce swelling.

Schumacher’s accident has prompted an outpouring of sympathy from racing stars and fans alike.

Former Formula One champion Niki Lauda, who himself suffered severe injuries in a 1976 racing crash, has also come out in support of the man known fondly as “Schumi”.

“I think there is someone up there who is trying to help him in this situation. At the time, I could help myself. Michael, though, cannot do anything for the moment,” he said in an interview with the Die Zeit weekly.

Schumacher was skiing in a small, off-piste section of Meribel located in between two slopes, full of half-buried rocks, when the accident happened.

A source close to a probe into the incident told AFP that his helmet, which medics say saved his life, had been smashed “in two” by the impact.

Kehm told journalists Tuesday that Schumacher was skiing “with a small group of friends” as well as his son.

She said he was not skiing at high speed when the accident happened. “He seems to have hit a rock as he took a turn. It was a chain of unfortunate circumstances.”

Schumacher towered over Formula One from his debut in 1991, winning more world titles and races than any other driver.