Eric Boullier is adamant Romain Grosjean has the "talent" and the "speed" needed to win a Formula One World title.
To many outsiders the Frenchman did not appear to be Championship material last season when his erratic driving and first lap stunts resulted in a one-race ban.
However, when Grosjean wasn't crash, he did show some speed, netting three podium finishes on his way to eighth in the Championship.
"I believe Romain can become World Champion," Boullier told The Guardian.
"That's why we kept him. Because we believe he's got the talent. He's definitely got the speed.
"The new Romain is a very different to the one three months ago. He's much more focused. He's not wasting any energy, any time on the useless things F1 can create.
"He is also one of the few drivers who has won every Championship he has entered. Lewis Hamilton achieved it, and so did Nico Hülkenberg. But Vettel has not. I'm sorry."
Boullier added that he believes Grosjean's erratic 2012 season was not due to a lack of talent. Rather, he says, it was because he was trying to hard after the disappointment of getting the axe in 2009 when Renault brought him in half way through the season.
"Last year he tried too hard. He wanted to show everyone that that was a mistake," said the team boss.
"But there were other reasons too. He didn't manage his time away from the track well. There were too many distractions. Even his marriage was a distraction.
"But now he's different. And he's proved he can win races and win Championships. So why not the Formula One World Championship?"
