Jenson Button has admitted that McLaren has taken a risk by replacing Sergio Perez with Kevin Magnussen for next season.
The 21-year-old Dane was announced as Perez's successor after the Mexican was axed from his position at the Woking-based team after one season, and Button warned his soon-to-be team-mate there would be no escaping the pressure once he gets behind the wheel in his first race.
"It's one of those positions where it could light up your career or put an end to your career very early if things don't go well," Button told Reuters ahead of this weekend's US Grand Prix in Austin, Texas.
"It's a massive risk to be put in the deep end, if you like, with a team that should be fighting for a title. But if a driver is willing to take that risk, he has a lot of confidence in himself and his ability.
"It could go one way or another and I hope it goes the positive way."
Magnussen is part of McLaren's young driver programme and was given the opportunity to replace Perez after winning this year's Formula Renault 3.5 Series.