Heidfeld unsure of future

Heidfeld, who has replaced dropped Spaniard Pedro de la Rosa, told a news conference that he had nothing settled for 2011.

However his brief stint as a test driver for new sole tyre supplier Pirelli, after also serving as Mercedes reserve this year, should stand him in good stead.

"It should be a help, having driven for Pirelli," said the 33-year-old veteran of 167 races who will be one of seven German drivers in Sunday's race.

"Some people would argue that it would have been better to stay testing and have even more of an advantage for next year but...when I had the chance to sign for Sauber for this year I definitely wanted to come back.

"I want to race, I believe I can do a good job," added Heidfeld.

"I've signed only for this season, the situation for next year is completely open with Sauber but also with other teams with which I have already been in talks over the last couple of weeks."

Heidfeld drove for Swiss-based Sauber from 2006 to last year when they were owned by now-departed BMW and also from 2001-2003.