Jenson Button faces the toughest challenge of his Formula One career when he joins Lewis Hamilton at McLaren next season and he knows it.

"Life is all about challenges and, most important of all, it's about challenging yourself," the 29-year-old world champion said after the Woking team announced he had signed a multi-year deal on Wednesday.

"Although I won the World Championship with Brawn GP last year, and I'll never forget that, I was always adamant that I wanted to continue to set myself fresh challenges."

The Briton will certainly get that at McLaren, where compatriot Hamilton is part of the family after being backed by the team since he was a bright-eyed kid winning titles in go-karts more than a decade ago.

Hamilton was a sensational rookie in 2007, seeing off double world champion teammate Fernando Alonso and ending the season as overall runner-up before becoming the youngest champion a year later.

His performances this season, wrestling with an uncompetitive car for the first half and then winning races in the second, have earned him even more admiration and respect.

Button is good, no question. He is one of the smoothest, most easy-going and least flappable drivers out there. However, Hamilton is young, hungry, fearless and well on the road to becoming one of the greats.

The 24-year-old has said he wants to take the title back from Button and he intends to do just that.

"I think it's a mistake by Jenson," Britain's triple world champion Jackie Stewart said.

"If I had been Jenson, I would have wanted to do a deal with Brawn because I know the culture of the Brawn team, I have a high respect for Ross Brawn, I would know the mechanics.

"There's a totally different culture in McLaren, something he might never have experienced before," said the Scot.

"It will be difficult for him to take on Lewis Hamilton. It's like walking into the lions' den ... Fernando Alonso couldn't cut it against Hamilton and I think Lewis will want to retain his position of prominence."

Whereas Michael Schumacher reigned supreme at Ferrari, McLaren have always given their drivers equal status even if - as with Hamilton and Alonso - that can sometimes backfire.

"In the past they (McLaren) have had a history of being able to only fully support one driver," said former McLaren racer Martin Brundle, who was David Coulthard's manager when the Scot partnered Finland's Mika Hakkinen.

"It's Lewis Hamilton's patch, it's his territory and he's made it his own. He knows everybody and knows where all the green buttons are to press."

While Button was comfortable at Brawn, loved by the mechanics and popular in the factory, that team will compete as Mercedes next year after a takeover announced on Monday.

That could well change the dynamics, with Germany's Nico Rosberg set to become the Stuttgart carmaker's favorite son and the suspicion Button was surplus to requirements.