Doctors treating Michael Schumacher stated that the injured former Formula 1 driver remains in "critical condition" following his skiing accident.The seven time world champion, who retired from F1 for the second time in 2012, sustained a head injury while skiing off-piste at the Meribel ski resort on December 29 2013. 'I AM VERY WORRIED'During a press conference, Chief anesthesiologist Jean-Francois Payen said: "He remains in a critical situation. He suffered a severe head injury which required immediate neurosurgical intervention. His injuries are serious. We cannot comment on his future."Doctors report that they will provide more information later on December 30.Payen said: "Everything that needed to be done has been done at the moment we can't really say when he will recover, we cannot answer this yet." "We can say he is fighting for his life. We judge him to be in a very serious situation. We cannot tell what the outcome will be yet. We are working hour-by-hour but it's too early to say what is going to happen and to have a prognosis.Schumacher arrived at the University Hospital in Grenoble, France in a coma on December 29 2013 and immediately underwent brain surgery. He struck his head on a rock after falling during a family skiing trip at the Meribel resort on December 2013. The 44-year-old was taken by helicopter to hospital in Moutiers before being moved to Grenoble.Schumacher is being treated by Professor Gerard Saillant, a brain and spinal injury expert and close friend of the injured driver. Saillant oversaw Schumacher's medical care when the veteran broke his leg during the 1999 British Grand Prix.We look back on the champion's F1 career!