Departing McLaren driver Lewis Hamilton insists he is "leaving home" in order to grow up.
The 27-year-old has spent his entire career with the Woking-based marque, including 2008 title victory, but will next season move on to pastures new, taking up a contract with Mercedes.
"It was the hardest decision I've ever made," Hamilton told the Mail on Sunday.
"It is to do with the process of growing up, of leaving home. That's why I am taking the next step, to grow as a driver and as a human being."
To some the move could look like a step down, with Mercedes having won just one race since their change of identity from Brawn GP in 2010.
Hamilton said: "The team I'm joining isn't yet performing well. But I hope I'll be able to help them get where they want to be."