Fans hold vigil for Michael Schumacher as he spends 45th birthday in coma
Schumacher suffered severe head trauma in a skiing accident in the French Alps on Sunday, CNN reports.
Since then, he has undergone two operations and is said to be in stable but critical condition at the hospital in Grenoble city.
Scuderia Ferrari, the racing team division of the Italian car maker, urged fans to join the vigil outside his hospital via its Facebook page.
People should dress in red and it will be "a silent and respectful event," the page said.
A French woman taking part in the vigil told CNN, "It's important to show support to Schumacher on his birthday and especially when he needs us most."
An Italian Ferrari fan, using the driver's nickname, said, "I've watched Schumi since I was a little boy and it means a lot to be here today."
The family of Michael Schumacher and car maker Ferrari both praised his fighting spirit as he battles to overcome his injures.
"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. They are giving us great support," his family posted on his official website.
Ferrari, for whom Schumacher -- the most successful driver in Formula 1 history -- won 72 Grands Prix between 1996 and 2006, also posted a birthday message on its website.
"This is a special day for Ferrari and all its fans, as it is Michael Schumacher's birthday," it said.
"At the moment, he is tackling the most important fight of his life and therefore we want to send him very special wishes."
Schumacher's manager, Sabine Kehm, said Wednesday that the driver was in a stable condition, but it's too early to speculate on his prospects for recovery.
He was catapulted head first onto a rock while skiing with family and friends in the resort of Meribel, she said.
On Monday night, doctors carried out a surgical intervention that relieved some pressure on his brain. They reported a slight improvement in his condition Tuesday, but he remained critically ill.
The University Hospital Center of Grenoble said doctors would not give an update Friday on Schumacher's condition unless it changed.