Nick Heidfeld will start the Singapore Grand Prix from the very back of the grid after his BMW Sauber entry was found to be underweight after Saturday evening's qualifying session.

The German had been due to line up in seventh place, having carried the lightest fuel load of anyone, but it was weight in another area that ultimately cost the German as the stewards deleted his effort.

With little to lose, the BMW Sauber team will take the opportunity to change Heidfeld's gearbox and engine, the former a move that would have incurred a five-place penalty similar to that which Rubens Barrichello suffered before qualifying. Heidfeld is also likely to start from the pit-lane rather than the outside of row ten.

His removal from row four, however, promotes BMW Sauber team-mate Robert Kubica to seventh on the grid, Heikki Kovalainen to eighth, Barrichello to ninth and Kazuki Nakajima into the top ten. Brawn's championship leader Jenson Button moves to the inside of row six after a disappointing qualifying session.