Former Formula 1 drivers Sir Jackie Stewart and John Watson believe world champion Jenson Button's decision to join McLaren next season is a mistake.
Button will drive alongside 2008 world champion Lewis Hamilton in an all-English line-up for the 2010 campaign.
"It's a mistake and will be like walking into the lion's den for Jenson," Stewart told BBC Sport.
Watson added: "It's hard to understand what it is about McLaren which Jenson Button wants to engage in."
Stewart, a three-time world champion, and former McLaren driver Watson agreed that Button faces an uphill battle to impose himself in a team where Hamilton is the established number one.
"Hamilton has had it his own way at McLaren for three years and it will be tough for Jenson to marry into that," said Stewart.
Putting himself in Button's shoes, Stewart, who won the world title in 1969, 1971 and 1973, added: "I would have wanted to do a deal with Brawn because I know the culture of the Brawn team and have a high respect for Ross Brawn and I know the mechanics intimately.
McLaren can handle this kind of ego and talent
BBC Sport pundit Eddie Jordan
"It's a totally different culture in McLaren. They have a clinical culture that doesn't have the emotion or drive in the same passionate way that say Brawn would have had with Button in there as reigning world champion.
"The McLaren car will be one of the best cars on the grid though, so he is going to a team that wants to succeed.
"However, Hamilton has had it his way. He disposed of Fernando Alonso and I think he will want to retain a position of prominence in team.
"He will be a tough guy for Jenson to marry into, whereas at Brawn he had the advantage of being with a team he's been with for a few years.
Button move a mistake - Stewart
"We are looking at two guys who want to be number one and in one team they are sometimes not perfect bed partners, because there will be differences."
Watson, who raced for McLaren between 1979 and 1985, thinks money was the key factor in Button's decision to leave Brawn.
"I think his heart was still really with the Brawn team," he said.
"I think he would have preferred to have stayed but the deal he was offered to him wasn't satisfactory.
"It didn't acknowledge the fact that he was world champion. I think he was hurt by that. McLaren came along with a much better offer but also it's a longer contract."
Watson was equally sceptical about Button's ability to challenge Hamilton's status at McLaren.
"I don't think Jenson has ever been matched against a driver of the quality, the ambition and out-and-out skill of Lewis Hamilton," he added.
"It is a challenge and Jenson will have to reassess his aims and objectives over the next three years, because for sure, Lewis Hamilton will not be a walk in the park."
Watson, who rates Hamilton as marginally the better driver, also questioned McLaren's ability to fashion a car suited to the contrasting styles of the two British world champions.
"Lewis is an out-and-out racer, I call him a hot rod. He just grabs a racing car by the steering wheel and drives his wheels off," he said.
"Jenson Button is more like an artist. His car is a palette and he uses it to paint a lovely picture of a driving style that is rhythmic, fluid, a joy to watch.
"But when the team has to work with two drivers which such diverse styles of driving, that's going to be difficult for McLaren to get their heads around."
However, BBC Sport pundit Eddie Jordan believes McLaren will be able to deal with having the last two world champions on their team.
He said: "The team was built for Hamilton and the whole McLaren team is behind him but Jenson brings something different to the team.
"There are two world champions, but McLaren can handle this kind of ego and talent."
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