The family of Michael Schumacher described the Formula One legend as a fighter who "will not give up", as he turned 45 Friday while lying comatose in a French hospital.
"Following Michael's skiing accident, we would like to thank the people from all around the world who have expressed their sympathy and sent their best wishes for his recovery," the Schumacher family said in a statement posted on the German racing great's website.
"We all know he is a fighter and will not give up" they added, in the message coinciding with his birthday.
Doctors and family members had been tight-lipped Thursday about the condition of the retired Formula One champion, who has been hospitalised since Sunday, when he slammed his head against a rock while skiing in the French Alps.
The Ferrari F1 team, where Schumacher spent many years, announced it would on Friday hold a "silent gathering" in front of the Grenoble hospital where he is being treated to mark the birthday of their ex-driver, who is being kept in an induced coma.
Schumacher has had two operations to remove bleeding and pressure on his brain.
Prosecutors have opened a probe into the accident, as is common practice in France in such cases, and are exploring the theory that Schumacher was skiing at great speed when he fell.
Schumacher, who made his Formula One debut in 1991, dominated the sport, winning more world titles and races than any other driver.
He first retired aged 37 but was unable to resist the lure of the track. In 2010 he came out of retirement but could not recover his previous levels of performance and quit for good in 2012.
As an F1 racer, Schumacher was known for his daring overtaking manoeuvres, his at-times almost reckless abandon in the pursuit of victory and his mastery of tricky conditions presented by rain.