Jenson Button says McLaren have taken a "massive risk" in promoting Magnussen

A day after Sergio Perez announced that he was leaving after just one season, McLaren confirmed recent intense speculation suggesting that Magnussen would replace the Mexican. The decision to pitch the 21-year-old headlong into the thick of the F1 fray represents a huge gamble on the part of the Woking team, but listening to Button speak on Thursday afternoon it sounds as though a fair degree of calculation is also involved.

"It's definitely one of those positions where it could light up your career or it could put an end to your career very early," he assessed.

"It's a massive risk for a driver, to be put in the deep end with a team that's fighting at the front, or should be. But if a driver's willing to take that risk then he's got a lot of confidence in himself and his ability.

"It could go one way or the other. I hope it goes the positive way because he's someone I want to work with throughout the year and he needs to be in a good frame of mind."

Magnussen has impressed team boss Martin Whitmarsh with his "lightning" speed but, of course, there's more to it than that - not least the exponential jump in a driver's understanding of how to extract performance from a car that's far more complicated than those he might have raced in junior formulae.

Then there's the effect next season's myriad rule changes might have. While Button has in the past stressed the value of experience in preparing for F1's biggest shake-up for a generation, he's trying to keep a more open mind where his new team-mate is concerned.

"I've always said all year with the new regulations, it's important to have a team-mate that's got experience. Kevin doesn't have that but his outright speed is very good but the bit that's more important for me is the tests he's done in an F1 car," he said.

"Looking at the data and what have you, his feedback has been very good.

"He's also been with this team a long time so he gets to spend time in the simulator and really understand how a Formula 1 driver works within a team - the input you need and the feedback you need to give.

"He needs that and needs to learn that very quickly if he doesn't have that already because we need to be strong from the first day of testing."

Magnussen, who graduates from Formula Renault 3.5, has said in the past that he sees the advent of 1.6-litre V6 turbo engines with enhanced energy recovery systems as an opportunity and Button acknowledges that the new coin has a flipside.

"One way is that experience doesn't count for so much these days because of the new regulations. It's a completely new way of driving a racing car - which it will be next year. So there's that way, and you'd say he's in a good position," he said.

"But then there's also the other side: with an experienced driver, he knows what he can do with a car to adjust it, to develop it and move it forward. In lower formulae you don't have that, you don't really change that much.

"You might change the set-up but in terms of driveability, you don't really have the electronics you have in a F1 car to work with.

"It's different but he's been to a lot of races this year, he understands how we work. So in terms of being ready I think he'll be ready for race one."

Button is also backing Perez but thinks the notion that the 23-year-old has received a raw deal in the shape of McLaren's underperforming MP4-28 has been overplayed.

"In terms of driving, I think he's come a long way this year. I think he's learned a lot. I think he's put in some good performances. The one that stands out is India. It's always difficult to compare yourself to someone who had issues in a race, but in India you have to say he did a very good job," the 2009 World Champion added.

"It's tricky but it's the business that we're in. We always have difficult years and it's very difficult to manage the situation when you expect to be somewhere else in the Championship and in a race.

"But as long as you do your best in every area, that's all that can be asked of you."