Michael Schumacher’s manager has moved to dampen optimism around a “slight improvement” in his condition.

Doctors said on Tuesday he had improved following a second operation to ease pressure on his brain.

But they stressed the 44-year-old – who remains critically ill – was not out of danger and the coming hours would be crucial.

Sabine Kehm, Schumacher’s manager, showing signs of strain on her face, warned against reading too much into what doctors were saying. She said: “I wouldn’t say that the doctors are very optimistic. I think they made it very clear that they’re not optimistic that they have to see that there was a slight improvement.”

Meanwhile Schumacher’s supporters have gathered outside the hospital in the French city of Grenoble, where he is being treated.

There has been an outpouring of concern for the former Formula One champion since he sustained head injuries in a skiing accident on Sunday.

“Schumacher is a very unique person, you know. And I think he will get well soon. He will win his last victory, his 92nd victory, I’m sure,” said one hopeful fan.

Schumacher’s father Rolf has joined the rest of the family by the bedside of the legendry formula one driver.

There has also been a steady stream of close friends visiting the hospital including French motor sport chief Jean Todt. But with doctors refusing to speculate on any prognosis, everyone leaving was keeping tight lipped.