Englishman Lewis Hamilton will drive for McLaren in Formula One next season.
Hamilton will make his F1 debut in Australia next March
The 21-year-old, the reigning champion of the GP2 feeder series, will be the first black driver to race in F1.
Hamilton, who has been in McLaren's young driver programme since 1998, said getting a drive with the team was "a dream come true".
He faces the daunting prospect of partnering world champion Fernando Alonso, who will be making his McLaren debut after moving from Renault.
McLaren boss Ron Dennis acknowledged that promoting Hamilton was a gamble, but insisted he was a better prospect than any driver in F1 other than Alonso and former McLaren driver Kimi Raikkonen.
"He has earned his chance and he deserves this opportunity," Dennis said.
"Yes, there's a concern," Dennis said. "But I'm open about this concern.
Statistically, Lewis is going to find it tough in the first few races of his Grand Prix career
"Both Lewis and the team have their eyes open and we will be very supportive. We have mapped out a very detailed programme to give him a grounding in all the different aspects of F1.
"By Australia [the first race], he will have been well prepared and well disciplined, and he will be as well equipped to handle it as we can make him."
Dennis said it was "not unrealistic" to expect Hamilton to win a race in his debut season "if we have a strong car, but certainly not in the early part of the season".
He added: "Statistically, Lewis is going to find it tough in the first few races of his Grand Prix career.
"You only have to look at the first few races of Ayrton Senna and Michael Schumacher to realise that unless he is something really exceptional, and that I doubt because they are two really exceptional drivers, you can't expect - and nor do we expect - immediate performance."
Hamilton's appointment means Spaniard Pedro de la Rosa will revert to being a test driver alongside another Englishman, Gary Paffett, who had been tipped for a race seat in another team.
Hamilton will join the McLaren team next week as they prepare for the 2007 season at the Circuit de Catalunya in Barcelona.
"To be racing in Formula One with McLaren has been the ulimate goal for me since I was very young," Hamilton said in a team statement.
"This opportunity is a fantastic way to end what has been the best year for me.
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"I'm aware that this will be a challenge and I know there will be a lot of attention on me," he added.
Hamilton, who joined the McLaren development programme at the age of 13, won the British Formula Renault title in 2003 and the Formula 3 Euroseries in 2005.