IRL IndyCar champions Andretti-Green Racing have signed rookie Hideki Mutoh to replace champion Dario Franchitti next year as the Briton heads off to NASCAR.

The 25-year-old Japanese driver, who was the runner-up in last year's Indy Pro Series, impressed the entire field with eighth place on his IndyCar debut in the final race of the season.

And AGR, co-owned by ChampCar legend Michael Andretti and Kim Green, wasted little time in giving him the fourth seat in the team alongside Marco Andretti, Danica Patrick and 2004 champion Tony Kanaan.

"In the (season finale), he was showing he could mix it up with the best side by side, working the traffic and still being sensible in the race car," said Green. "We're just delighted to have the opportunity bring him on board and hopefully take him to that next level, which is the winner's circle.

"He starts in our training program right away. He'll be spending a lot of time at the race shop, which is great for him from a communication standpoint. We'll then be trying to get into an in-depth rookie test schedule before the season."

Filling Franchitti's shoes will be a tall order for Mutoh, as the British star spent his entire IndyCar career with AGR after switching from ChampCar in 2003, and won eight times in 67 races on his way to last year's title and Indy 500 victory.

But the newcomer has slated 2008 in as a learning year first and foremost.

"I hope to gain a lot of experience from my teammates," said Mutoh. "It's very exciting. The team's record is very impressive and I am hopeful that I can contribute to its future success."

Mutoh began his career in Formula Vauxhall Jr and Formula Ford in Britain, finishing third in the 2001 Formula Ford Festival at Brands Hatch.

The 2003 Formula Dream title in his homeland led him on to two years of Japanese Formula Three, in which he won a handful of races on his way to third overall in 2005.

A Super GT campaign a year later led to a move to the USA and second place in last year's Indy Pro Series behind Britain's Alex Lloyd.

Jamie O'Leary / Eurosport