Williams will try out the teenage sons of former champions Nelson Piquet and Keke Rosberg next week to see whether they have what it takes to drive for the Formula One team.

Williams said in a statement that Nelson Piquet junior, Nelsinho, would test at Jerez in Spain on December 2 and 4 with Nico Rosberg running on December 3 and 4 alongside Ralf Schumacher and regular tester Marc Gene.

"We are testing with the young drivers to evaluate their ability in an F1 car and whether or not they could assist with our testing programme in the future," said Williams chief operations engineer Sam Michael.

"They have been working with us over the last couple of months to ensure they are well prepared for the test and it's clear already that both are quite mature in their approach."

Rosberg, 18-year-old son of Finland's 1982 champion for Williams, tested for the team last year after winning the 2002 German Formula BMW championship.

That one-off outing made him the youngest driver to experience the power of a Formula One car and he left a strong impression on the team.

Nelsinho, who raced against Rosberg for the first time at this month's Macau Formula Three Grand Prix, will be having his first taste of a Grand Prix car.

The 18-year-old, whose father won the last of his three titles in a Williams in 1987, came third overall in his debut season in British Formula Three after dominating the South American championship.

Piquet senior told Brazil's Globo television on Wednesday that Williams were interested in signing his son to 2010, with two years as a test driver followed by five as a racer.

Williams, championship runners-up this season, have a much-sought after vacancy at the end of next year after McLaren announced this month that they had signed Colombian Juan Pablo Montoya for 2005.