Rosberg confirmed at Williams

The 20-year-old son of 1982 World Champion Keke Rosberg, who was born in Germany and races under that country's flag, will partner Australian Mark Webber at the Cosworth-powered team.

"I believe I am only one of many in Formula One who is genuinely excited about the prospect of Nico Rosberg," said team boss Frank Williams.

"Given the attention he commands, I am delighted he is making a contribution to Formula One history and has signed with us for next season."

Rosberg's appointment, as the youngest driver on the starting grid, follows Briton Jenson Button's decision to buy himself out of his contract with Williams so that he could remain at Honda-backed BAR.

The announcement ended the hopes of Brazilian Antonio Pizzonia, who replaced Germany's Nick Heidfeld for the last five races of the 2005 season. Heidfeld will be racing for the new BMW team next year.

Rosberg, who will be the first son of a champion to race in Formula One since Briton Damon Hill retired in 1999, won the inaugural GP2 support series this season.

Already the youngest person to drive a Formula One car, having his first test with Williams at the age of 17 in 2002 after winning the German Formula BMW title, Rosberg is Germany's fourth confirmed driver for the 2006 season.

Williams said he had been chosen for several reasons, not least his race craft.

"His natural talent in the cockpit is equally matched by his intelligence out of it, demonstrated by his depth of technical understanding and communication of data over the months spent as a test driver this season," a team statement said.

"Despite his youth, his wealth of experience reflects the early start made by contemporary drivers and it is significant to note that Nico has recorded more race starts by the age of 20 than his father...recorded in an entire career."

Finland's Keke Rosberg won the world championship with Williams, despite only one victory in that season, and retired in 1986 with five wins from 114 starts.

Rosberg junior will start his new duties for the team in winter testing, with the debut run of their new Cosworth V8 engine in Barcelona scheduled on November 29.

"I am really looking forward to starting work at the end of this month and learning as much from the team as I possibly can," said Rosberg.