Sebastian Vettel says he may quit Formula 1 in five years' time.
The 25-year-old German has dominated the sport in recent years, wrapping up each of the last three Drivers' World Championships.
Vettel is well positioned to make it four in a row currently, and is 21 points clear of Louts driver Kimi Raikkonen at the top of the standings after six races following his 2nd place finish at the Monaco Grand Prix last month.
The Red Bull driver admitted he may not still be in the sport in five years time when quizzed about his future at the Milton Keynes-based team.
"I can't say [about my long-term future at Red Bull]. Perhaps I will no longer be driving in five years' time because I no longer have the urge to," he told German newspaper Welt Am.
"Perhaps I will compete for another team in five years because I feel ready for a fresh challenge. Every human being evolves as time goes by, priorities shift.
"Right now I feel completely at ease here and I could not imagine driving anywhere else.
"The car is quick, the team does well - I see no reason to leave. But that does not automatically mean I will stay forever."
Vettel is contracted with Red Bull until the end of next season, and has previously been linked with a move to Ferrari.
Of more pressing urgency for Vettel is the identity of his team-mate for next season.
Australian Mark Webber, who shares a fractious relationship with Vettel, could leave to make way for Raikkonen in 2014, or even a driver from Red Bull's feeder team Torro Rosso.
Asked whether he would like Raikkonen as a team-mate ahead of the Canadian Grand Prix this weekend, he replied: "I don't know how realistic that is. But I get along very well with him."