Jenson Button has admitted that this week's news that Sergio Perez would leave McLaren at the end of the season and that Button would be joined in Woking by 21-year-old rookie Kevin Magnussen had taken him somewhat by surprise.

"I'm always surprised by F1 and things that change," said Button. "I was surprised last year when Lewis decided to leave and I think the same now. But it's what F1 is like; things change and we learn to adapt."

Button went on to describe the signing of the Formula Renault 3.5 title winner to race alongside him in 2014 as a huge career gamble for the young Finn.

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"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," said Button in Austin on Thursday ahead of this weekend's United States Grand Prix.

"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 added, perhaps thinking of what's happened to Perez in the past 12 months as he spoke. "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," Button mused. "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."

One thing that could sway things in Magnussen's favour is that all the new technical regulations in 2014 will mean that everyone will be heading into the unknown next season regardless of how many years they've been in the sport.

"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 explained.

"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," he pointed out. "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."

"Kevin doesn't have that but I think his outright speed is very good and the bit that is more important for me is from the tests that he's done in an F1 can and looking at the data and what have you his feedback has been very good, which is going to be very important at the start of the year.

"We get equal days in the car and it's important that his feedback is good, having confidence in that," he said. "I know a little bit about him and the way he goes racing and his speed but also the way that he works with the team.

"It is an exciting challenge for all of us next year and having Kevin on board with his speed and his determination I think is good for the team."

Magnussen's status as a McLaren junior has seen him get plenty of time to soak things up by attending Grand Prix events in 2013. ""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," agreed Button.

"He's also been with this team for a long time so he gets to spend time in the simulator and really understand how a F1 driver works within a team and the input and feedback that you need to give a team. He needs that and he needs to learn that very quickly if he doesn't have that already, because we need to start from the first day of testing to be strong and already start developing the feel of everything in terms of the engine, the power unit and also the car."

The 2009 world champion has at least known that his own race seat for 2014 was secure after signing a year-long extension to his existing contract last month, whereas Perez grew increasingly anxious over the months as his contract renewal appeared perpetually imminent but which never actually materialised.

"It's tricky but it's the business that we're in," said Button, sympathetic to Perez' plight but also realistic about the circumstances. "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," Button added. "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 way that he's learned throughout the year and improved himself in terms of speed, in terms of being a racing driver, developing the car, tyre management and what have you - he's really picked up a lot this year and learned a lot," he added. "He's definitely been on a steep learning curve."

Overall, Button's philosophy of F1 - whether for himself or applied to Perez or even new boy Magnussen - is simple: "As long as you do your best in every area, that's all that can be asked of you."