Sebastian Vettel has warned that he cannot afford any more engine failures after losing another one of his eight unit allocation for the season in free practice on Saturday.
The Red Bull driver had already brought six of his engines into play when he suffered the failure, leaving him with just two fresh ones to deploy during the final six races of the season.
Although teams regularly swap their engines around and are able to bring back powerplants that have been used before, Vettel could face having to take a ten-place grid penalty at the first event where he brings a ninth unit into play. He is understood already to have lost at least one other Renault engine to a failure.
"From now on, there is no room for any more failures or mistakes," said Vettel when asked by AUTOSPORT how concerned he was about his engine allocation.
"I can't change anything now. Of course, if you want to win the championship it is not a good thing towards the end of the season because it will get tight. How tight, we will see."
Despite being pleased with the progress that Red Bull made between Friday practice and qualifying, Vettel fears that the resurgence of McLaren-Mercedes will make it harder to chase down Jenson Button and Brawn in the championship. He also pointed to the McLaren KERS as a major factor in the team's speed.
"If there is someone who is taking big points, it's not easy to catch up when you are hunters like us," said Vettel. "But let's see what happens tomorrow. Fourth on the grid is not a disaster and no-one has scored any points yet.
"On this circuit last year everyone was close -- for instance Force India is not far off. It's not a secret that if you have something on board [like KERS] that is worth three of fourth tenths, the rest cannot find a part that gives that much of a jump."