Nico Rosberg claims Hamilton's arrival at Mercedes is not a worry

Rosberg has been the most successful Mercedes driver over the past three seasons, but the arrival of the 2008 world champion is expected to threaten his position.

But the 27-year-old is relishing the challenge of taking on his former karting team-mate with the German marque.

"I'm looking forward to it because I enjoy these sorts of challenges," said Rosberg. "I'm confident I will do well and I'm pushing hard to do well.

"[How I] compare with my team-mate remains to be seen. I'm not worried.

"At the moment, my team-mate is a seven-times world champion, so the challenge I'm up against is very high.

"I remember racing him [Lewis] in go-karts, so I now it's tough up against him. He's very very quick and one of the best out there at the moment."

Rosberg admitted that he did talk with Hamilton, who he has been friends with since their karting days together, about the possibility of a move before the deal was struck.

But he denied talking Hamilton into the move, insisting that he only gave his honest appraisal of the potential of the team.

"We spoke about it a little before, when the possibility was there," said Rosberg. "We were laughing about it!

"And we spoke about it when we were 14 years old in go-karts. 'Imagine if, one day, we're team-mates in F1, how cool would that be?' Now, all of a sudden, that's happening, which is unreal.

"I didn't necessarily talk him into it. I tried to stay quite objective. Yes, I mentioned the positives but he asked me a few things and I gave honest answers.

"My answers are all positive because I am positive about the team. I believe in this team fully."

But despite the pressures of the pair lining up together in a sport where your first rival is said to be your team-mate, Rosberg has no doubts that their relationship will stand up.

"Comparing [yourself] to your team-ate is very important," said Rosberg. "In general, we aim to separate the things out a bit - friendship outside and racing competitively against each other.

"We managed that very well in go-karts already so I don't see any issue or concern there. We were team-mates for two years and we even shared hotel rooms. It went very well."