Gina Maria Schumacher, 20, took to Instagram to write a heartfelt message to her father to mark his 49th birthday yesterday.
She wrote on the social networking site: “Happy Birthday to the best Dad ever. We love you. #keepfighting.”
The message came as the motor racing star’s old Formula 1 team Ferrari took to Twitter to pay homage to the seven-time world champion.
The Italian team wrote on Twitter: “Today Michael turns 49, our thoughts are always with him. #Keepfighting #ForzaMichael.”
The German motor racing star, who has a worldwide fan base, was left fighting for his life after a skiing accident in the French Alps four years ago when he suffered catastrophic head injuries.
Michael Schumacher was put into a medically-induced coma after he fell and hit his head on a rock while skiing with his son at the Meribel resort in the French Alps on December 29, 2013.
In the wake of the crash, the record-breaking Formula 1 driver underwent two life-saving operations at Grenoble Hospital, before being transferred to a medical facility in Lausanne, Switzerland in April 2014.
He was discharged from hospital in September 2014 and is believed to be constantly cared for at his home in Switzerland during his rehabilitation.
Although details are scarce it is believed he is being nursed back to health by Mr Schumacher’s wife Corinna, 48 as well as his children Gina Maria and son Mick, 18.
His family has closely guarded his privacy and released very little information on any possible recovery.
His condition is currently unknown, but it is believed he is being rehabilitated at his family home in Switzerland.
Mr Schumacher’s family was given new encouragement yesterday after a medical expert urged them to not “give up hope”.
Professor Mark Obermann, Director of the Centre for Neurology at the Asklepios clinic in Seesen, Germany highlighted a new study, saying there were good results for patients in a persistent vegetative state.
Prof Obermann said: “According to a Swedish study, between 30 and 40 percent of patients have regained consciousness within four years.”
Although he added that did not mean the patient will make a full recovery, he said: “Many can come back to life and see how their children and grandchildren grow up, what plans they have or what else happens in the family or in the circle of friends.”