F1 legend Sir Stirling Moss has urged Lewis Hamilton to reunite with his father.
Although the pair have patched up their personal relationship, McLaren driver Hamilton - guided into F1 and through his championship year by his father - is no longer managed by Anthony Hamilton.
Moss, 81, said he is concerned with Hamilton's current behaviour.
"I am very concerned about him because I think he is an enormous talent," he told the Daily Mail.
"It would appear to me that his persona has changed since he moved away from being with his dad," added Moss, referring to Anthony, who now manages Force India rookie Paul di Resta.
Hamilton has been under fire in 2011 for on-track driving incidents and the way he has reacted to that criticism.
"I quite understand it is the bravado of youth and all that, but it is pretty dumb and he is not dumb," Moss insisted. "You can't be a world champion if you are stupid."
Hamilton's teammate Jenson Button declined to weigh in on the 2008 world champion's situation.
"He will always be quick. It is about whether he is happy within himself and that's for him. I see him when we do events and when we are at the circuit (but) I don't sit down with him as friends," he said.