Vettel fastest under Singapore lights

Vettel's lap, however, was almost 1.3 seconds slower than his best of yesterday as the high humidity of 81% - nine per cent up compared to 24 hours earlier - again played its part.

It ensured the track took its time to dry, despite temperatures at 28 degrees centigrade, following a customary afternoon downpour.

That had occurred three hours prior to final practice commencing under the bright lights of the Marina Bay street circuit, offering a clear idea as to how long the track remains damp.

Despite many dry areas, there were many others that were greasy due to the conditions, notably on the approach to turn four.

That is where Lewis Hamilton, Mark Webber and Nico Rosberg were all forced to use the run-off area as they failed to turn in time under braking.

But as yesterday, Red Bull's Vettel was again 0.6secs quicker than his rivals, on this occasion led by Ferrari's Fernando Alonso.

Vettel, 24 points behind championship leader and team-mate Mark Webber is in desperate need of a good result to close the gap on the Australian.

Pole, though, has not been an advantage for the 23-year-old as he has won only once from his previous seven occasions when starting from top spot on the grid.

Behind the leading duo were Hamilton in his McLaren and the second Ferrari of Felipe Massa who were both just under a second down on the German.

Rosberg was fifth quickest in his Mercedes, with Webber sixth, the 34-year-old 1.184secs adrift of Vettel, a position he will not want come qualifying.

William's Nico Hulkenberg, Robert Kubica in his Renault and Adrian Sutil were seventh, eighth and ninth, with Toro Rosso's Sebastien Buemi 10th, the only other drivers within two seconds of Vettel.

There were no concerns for Sutil today after his flying excursion yesterday when he struck a kerb through the turn 10 chicane that was described by Hamilton as "the worst corner I've ever driven in Formula One".

Landing on his front-left wheel, the impact broke the suspension, after which Sutil tried to continue for around a third of a lap.

That incurred the wrath of the FIA who fined the German 10,000 US dollars for not leaving the track as soon as it was safe to do so.

Reigning world champion Jenson Button was a surprisingly low 13th in his McLaren, just over two seconds off Vettel, with Michael Schumacher 15th for Mercedes.

Bruno Senna struggled in his Hispania, clipping a barrier at the very end of the hour-long session and finishing over seven seconds down.