Robert Kubica may be left ruing his decision to ditch BMW Sauber's KERS system after just a handful of practice sessions after failing to make it through the opening phase of qualifying at the Chinese Grand Prix.

The Pole decided, ahead of the knock-out session, that the option of extra power was out-weighed by his own weight, but failed to break out of the bottom five in the final moments of qualifying and will start Sunday's third F1 event of the season from 18th on the grid. Having fallen through the trapdoor into the drop zone, the Pole had one chance to make amends, but improved only to 16th and was then pushed back by improvements around him.

Kubica could have been joined in the bottom five by KERS-assisted team-mate Nick Heidfeld, but the German made the mot of his final flying effort to go twelfth, dropping Toro Rosso's Sebastien Bourdais in among the condemned. The Frenchman reported running wide on his last-ditch lap, scotching any chance of an improvement, while team-mate Sebastien Buemi showed what the STR4 was capable of in eighth.

Kubica and Bourdais were joined going through the exit door by the two Force Indias and Nelson Piquet Jr, the Brazilian becoming a regular early visitor to the sidelines, and surely casting further doubt on his continued participation in the top flight. Heikki Kovalainen and Kazuki Nakajima came closest to the chop, but survived by three tenths.

Fastest time was fought over by more than half a dozen drivers - including Nico Rosberg, Sebastian Vettel, Mark Webber, Lewis Hamilton, Kimi Raikkonen, Felipe Massa, Jenson Button and Rubens Barrichello - before the world championship leader finally emerged on top in 1min 35.533secs.