Webber has fresh engine advantage over title rivals

From the perspective of spare fresh engines in the bank, championship leader Mark Webber has an advantage in the five-race run to the 2010 finale.

Ferrari's Fernando Alonso and Felipe Massa have each used their full allocation of eight engines for the season, meaning that if they need to use more engines in 2010, they will incur ten-place grid penalties.

"We preferred to use a new engine at Monza and then manage the mileage for the next five races," team boss Stefano Domenicali is quoted by La Gazzetta dello Sport.

McLaren's Lewis Hamilton and Jenson Button have used 7 engines apiece, so they each have a spare engine in the bag.

"The McLaren drivers (are a threat) because they look to have a bit more reliability up their sleeve with engines, and we don't know what's going to go on at the end of the year," Webber said in an interview with BBC Sport.

Also having used 7 engines so far are the Mercedes, Force India, Toro Rosso, HRT, Virgin and Lotus drivers, Williams' Nico Hulkenberg and Sauber's Kamui Kobayashi.

Sebastian Vettel has a spare Renault engine in the bank, but Webber has two fresh engines still to fit in the rear of his RB6.

"Singapore should suit us if Monaco is anything to go by," said the Australian, who won that famous street race in May.

"We've seen performance move around a little bit - not much - against the form card but on paper the next few circuits look like they should be good for us," added Webber.

Also with two spare engines left are the works Renault drivers, and Williams' Rubens Barrichello.

Sauber's Pedro de la Rosa, meanwhile, ran out of engines in Belgium last month, forcing him ten places down the grid after a ninth Ferrari unit was installed.

Nick Heidfeld is now taking over car number 22, meaning that if a tenth engine needs to be fitted at any of the five remaining races this season, it will be the German serving a grid penalty.