Rosberg's last race for Williams will be at the Yas Marina Circuit in Abu Dhabi [EPA]

Rosberg has not yet confirmed which team he will join in 2010, but it is thought either Brawn GP or McLaren are the top contenders for the German's future career.

Rosberg, son of Finland's 1982 world champion Keke, refused to say which team he was switching to.

He is currently seventh in the drivers' standings after 16 races, having scored all of his team's 34.5 points.

Career change

"It is my last race with Williams,'' Rosberg said.

"Four or five years with the only team I have worked with - it's going to be quite strange to leave.

"They have really supported my career, so it's a 'thank you' for them.''

Rosberg said he was eager to join a team that had the potential to win races next season - something he thought was beyond Williams.

"I would like to try to get into a car where there would be a very good chance of winning,'' Rosberg said.

"There is no reason they (Williams) can't be as good next year as this year and remain close to the top, but I am not sure they can win races.''

Brawn GP driver Rubens Barrichello has held talks with Williams about joining in 2010 and is considered the most likely contender to replace Rosberg, raising the possibility of a straight swap between the pair.

Should the 24-year-old Rosberg move to McLaren, he would reunite with Lewis Hamilton.

The pair drove together for a McLaren Mercedes junior karting team, but the German denied he had any ongoing contractual link to Mercedes which had prompted a 2010 shift.

"I have no ties,'' Rosberg said.

Williams, who last won a race in 2004, are expected to have an all-new line-up next season with Brawn's Brazilian Rubens Barrichello and German rookie Nico Hulkenberg tipped by the media to replace Rosberg and Japan's Kazuki Nakajima.