During his junior career, Sebastian Vettel had a level of professionalism comparable to Michael Schumacher, ex-BMW chief Mario Theissen claims.

The four-time world champion had a close affiliation to the German manufacturer before achieving his success at Red Bull, notably debuting in Formula 1 with BMW at the 2007 US Grand Prix.

Prior to that, Vettel was a test driver at the team and throughout their time working together, Theissen noted how Vettel had an approach that was well beyond his years.

“As young as he was then, he was extremely mature. He was clearly ahead of the others in terms of professionalism and focus,” he told Motorsport-Total.com

“He prepared himself, did other sport and his fitness programme was also above all others. He wasn’t interested in anything else, he put his heart and soul into it and that was absolutely impressive.”

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Vettel's attention to detail is something that he's carried to this day and has even sometimes led to friction with Ferrari, with a feeling he was getting too involved.

Theissen though believes that is something the 32-year-old shares with his hero.

“I’m not as close to him now as I used to be, but a person’s character doesn’t change. I’m sure the professionalism with which he approaches people hasn’t changed either," he commented.

“He has much of what you saw a generation before in Michael Schumacher.”