The German has been in poor form in 2019 and is fifth in the driver’s championship, with Leclerc overtaking him in the rankings after winning the Italian Grand Prix on Sunday, to much fanfare from the Scuderia supporters.
The Monegasque driver has now won two races on the bounce, with many pundits and fans now viewing him as Ferrari’s number one driver.
The situation has echoes of Ricciardo’s arrival at Red Bull while Vettel was a four-time world champion, according to Brawn.
"It's an unavoidable fact that no matter who the driver is and regardless of how good things are in the team, your first rival is always your team-mate,” he wrote in his Italian GP review.
“To a certain extent, Sebastian is experiencing what he felt at Red Bull in his final year there, in 2014, when he found himself up against Daniel Ricciardo, a youngster setting incredible pace."
The former Ferrari technical director believes that the team need to get Vettel firing again so they can finally put some pressure on Mercedes next season, with the constructors’ championship this year looking all but over.
"Vettel is clearly one of the greats of our sport, but at this tough time he really needs the support of the team to regain the confidence he seems to be lacking at the moment," Brawn insisted.
"That, as well as pushing on with the car development, has to be a priority for Mattia Binotto in the coming weeks.
"It won't be easy, but it is essential especially in terms of 2020."
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