Lewis Hamilton will quit Formula 1 when his "private life" becomes more important to him, according to former F1 driver Marc Surer.

Hamilton, who recently commented on potentially quitting the sport, is reportedly negotiating a lucrative new deal with Mercedes to take him beyond his 2018 contract.

However, Surer told Sky: "I also think sometimes that he's so distracted by his private life.

"One day he could say 'Oh man, do I have to go and race again?' I think that could happen to him any time."

Surer also thinks that Hamilton will only now be motivated if he is pushing for a title, as was demonstrated in the last races of 2017 when Valtteri Bottas had the edge.

"Bottas is just in a different category to Hamilton," he said. "We saw that clearly this year.

"If Lewis is serious, Bottas lacks something to him."

Hamilton will enter the 2018 season a four-time champion after this year's success.