Rosberg sorry to miss out on points

The German qualified ninth and and took advantage of Robert Kubica's spin to move ahead of the Pole, but was jumped by one-stoppers Kamui Kobayashi and Sebastien Buemi and finished the race outside the points.

"I would have liked to help the team hold on to sixth place in the Constructors' Championship," said Rosberg. "From a personal perspective, my seventh place in the driver's table wasn't challenged and I think this was a good result this year in the circumstances.

"It's been a long season and I would really like to thank all the team for their effort during the last four years. We have had a great time together."

Chief operations engineer Rod Nelson blamed getting stuck behind Jarno Trulli's Toyota for Rosberg failing to improve ninth place, although even if the German had got ahead of Buemi the team would still have missed out on sixth place in the Constructors' Championship to BMW Sauber by half a point.

"It was naturally disappointing not to be able to retain our championship position today, but well done to BMW," said Nelson. "We will miss them next year.

"The car wasn't quick enough and a few incidents in the race compounded the situation. Losing time behind Trulli meant the one-stopping Kobayashi could get ahead of Nico, which made it very difficult to maintain our points margin."

Kazuki Nakajima, also in his final start for Williams, rounded out a pointless season with 11th place and blamed a difficult first stint for his failure to get into contention for a top eight finish.

"It wasn't easy running on a one-stop today and I didn't feel that the first stint went well," said Nakajima. "The middle of the race was more affected by traffic, but there was nothing to do except keep plugging away for 55 laps, but it was a good battle and I enjoyed myself."