Nico Rosberg needs to "start from scratch" as he tries to take on teammate Lewis Hamilton in 2015.

That is the advice of Mercedes' team chairman Niki Lauda, who is also one of the most famous names in F1 history.

After fighting Hamilton hard throughout 2014, German Rosberg has notably struggled this season and is already 27 points behind after four races.

Austrian legend Lauda, a former triple world champion, sympathises.

"Nico has the hardest job imaginable," he told Germany's Auto Motor und Sport. "Lewis is in top form at the moment -- he makes virtually no errors and his self-confidence is boundless."

Rosberg, on the other hand, is known as the ultimate F1 'thinker', so that after losing to Hamilton by six tenths in Bahrain qualifying, he tried to over-analyse the reasons.

But "He should forget the complicated explanations and just say 'I made a mistake'," Lauda advises.

"Get the ballast out of your head and do your race as though the world championship is starting from scratch every time."

Another former F1 driver, Gerhard Berger, says Lauda's advice will be useful to Rosberg.

"It's ok for him (Rosberg) to ask Niki how to become champion if you apparently don't have the speed of your rival," he said, probably referring to Lauda's famous half-point victory against McLaren teammate Alain Prost in 1984.

"Above all, Nico must continue to believe in himself," Berger added, according to f1-insider.com. "That's the most important thing."

Lauda, meanwhile, says the most important thing for Rosberg is to urgently put a stop to Hamilton's run of form.

"Nico has to break this run from Lewis," he insisted, "and put him under pressure. If he beats him just once, then the other one (Hamilton) will start to think about it."

(GMM)