This winter is the most important of Vettel's career

Vettel was outperformed by his younger teammate, Charles Leclerc this season and the German finished down in fifth in the Drivers' Championship. The former-Red Bull driver's only victory this season was his controversial victory at the Singapore Grand Prix.

Webber drove with Vettel during their time at Red Bull and believes he faces a huge fight to bounce back next season.

"I think this is definitely the most important winter period of his career," Webber told Channel 4.

"It was his worst season at Ferrari and he will have to fight a huge fight to come back next year.

"He is a winner, a fighter, but a small flaw in his armory is the fact that he is not a great listener. I think that he has to ask some people for advice. This is uncharted territory for him because he is approaching the end of his career.

"He must also ask for all possible professional advice that he can get from people who have also followed this path."