Triple world champion Sir Jackie Stewart believes Jenson Button has been unwise to move from Brawn to McLaren.
"It will be difficult for him to take on Lewis Hamilton," said Stewart. "It's like walking into the lion's den, because Lewis has had three years with McLaren now. He has it his way.
"He's already disposed of one driver that came in there in Alonso. Fernando couldn't cut it against Lewis Hamilton, and I think that Lewis will want to retain his position of prominence in that team. Whereas at Brawn, I think [Button] would have had an advantage over his [potential] team-mate Nico Rosberg, having knowledge of the team.
"What we're looking at today is two guys who want to be number one. That situation in one team sometimes makes imperfect bed partners, because there will be differences from time to time, even though McLaren are probably the best engineering team with the most capacity to do the job."
Stewart also thinks Button underestimated the value of the strong relationship he had established with Ross Brawn's team.