On paper, Sebastian Vettel is the overwhelming favourite to seal his third consecutive drivers' crown this weekend in Brazil. His 13-point lead over Ferrari's Fernando Alonso means he can steer his ...

On paper, Sebastian Vettel is the overwhelming favourite to seal his third consecutive drivers' crown this weekend in Brazil.

His 13-point lead over Ferrari's Fernando Alonso means he can steer his ultra-competitive Red Bull to just fourth place at Interlagos and still set off for his winter slumber with the title.

"But Alonso still must win," Red Bull's Dr Helmut Marko is quoted by Speed Week. "He must take the risk. That's the important thing."

But it's not quite as simple as that. First, there is the pressure of the season finale, with Alonso a hardened, never-say-die samurai-loving competitor.

And Marko acknowledged that Brazil is often a "crazy race", even without the forecast high probability of rain.

But the Austrian insisted: "The only question mark is reliability. So no, I'm not relaxed."

Marko is undoubtedly referring to Red Bull's recurring alternator failures in 2012, the latest of which struck Mark Webber's car in Austin.

It was believed Renault offered Red Bull a brand new specification of the Magneti Marelli unit for the US grand prix, but in fact the reigning champions opted for the tried-and-tested previous version.

Spain's Mundo Deportivo newspaper said Red Bull will definitely use the brand new specification for the Sao Paulo finale.

"We are ready with the new one," Renault's Remi Taffin is quoted by Brazil's Globo Esporte.

"Generally we feel more comfortable with something we have known for a long time, but we have tested the new design and so there's no need to be worried," he added.

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