Michael Schumacher could remain in a "persistent vegetative state" for the rest of his life, an Austrian website has reported.
The Formula One star has been in intensive care since a skiing accident in France nearly four weeks ago.
The Daily Mail reports that Jean-Marc Orgogozo, Professor of Neurology at the University of Bordeaux, said: "Every day, every week in a coma the chances decline that the situation is improving."
The format.at news website reported that Schumacher may suffer apallic syndrome, or persistent vegetative state.
His condition is currently stable but experts have speculated that his fall caused severe brain damage, the Daily Mirror reports.
Writing on his webpage on Tuesday, his family said: "We all know: he is a fighter and will not give up! We are deeply moved that there is no let up in the good wishes for Michael from around the world.
"That gives us strength. Thank you all of you!"
Reporter faints in snow on live TV and wakes up to finish ski interview