Rosberg made his testing debut with the team in 2002 at the age of 17, becoming the youngest man to ever pilot a Formula One car.
However, following his 2005 championship season in the newly created GP2 Series, Rosberg finally got his big Formula One opportunity with Williams F1, who chose to pair him with Mark Webber for the 2006 campaign. For Rosberg, it was a return home as Williams was the team that his father, Keke Rosberg, won the championship with in 1982.
While only scoring four points in his rookie season, the German born driver had impressive drives throughout the season – including at the season opening Grand Prix of Bahrain, where he finished seventh and had the fastest lap of the race (becoming the youngest driver in history to record a fastest lap).
In 2007, he again raced with Williams and showed a much quicker side of himself, securing 10 top-10 grid starts. He scored 20 points and finished ninth in the final standings.
