Nico Rosberg has the knives sharpened for Lewis Hamilton

London: Nico Rosberg says he has sharpened his knives for the new Formula One season and is ready to take on champion Mercedes team mate Lewis Hamilton and anyone else who fancies their title chances.

The German, runner-up last year as Hamilton collected his second crown, told the official formula1.com website that he felt stronger than ever and was sure the new Mercedes was better.

Asked whether he already had his metaphorical knives "sharpened" for the season, Rosberg said he had started doing that as soon as the last campaign ended in Abu Dhabi.

"For now it is Lewis -- and whoever else wants to have a go at the knife," he added with a laugh when asked about the main target.

The two Mercedes team mates, who have known and raced against each other from boyhood, had a tense relationship last season as they battled for the title.

Rosberg expected more of the same.

"We have a relationship that goes up and down -- and it will continue to go up and down," he said. "It is an intense battle between us and that will not change any time soon.

"Last year`s experience helps," he added of this year`s challenge. "It`s that `been there, done that` kind of thing. All the difficult times have made me stronger. It is the difficult moments where I learn the most."

The German said Hamilton, who won 11 races last year to Rosberg`s five, had simply performed better in 2014.

"He drove better all in all. Small bits here and there -- and I need to find small steps to beat him. And I am going for it," he said.

Mercedes will start the season in Australia on March 15 as clear favourites again and the new car has looked strong in testing in southern Spain, although Hamilton was stopped by a water leak on Monday.

Rosberg did almost 700km and 157 laps on the first day at the Jerez circuit, far more than rivals, and said the car was "even better than last year`s".

His dream year, he said, would be a great start followed by "a tough part by mid-season when I lose touch -- and then an awesome comeback in the end, winning all the races to total dominance."