Motorsport.com revealed on Thursday that Ferrari had used one of its remaining four tokens ahead of the Austrian Grand Prix, with sources suggesting the focus had been on a revised MGU-K.

However, the Maranello outfit has now explained that instead the work has focused on a revised camshaft within the engine itself.

There is no official explanation for why the change to the camshaft has been made, but it could be associated with a new specification of fuel that Shell is introducing that is expected to deliver a decent horsepower boost

Token use

A notice issued by the FIA confirmed that both Vettel and Raikkonen will start with fresh internal combustion engines on Saturday. It will be Vettel's fourth unit of the season and Raikkonen's third.

They will also be fitted with new MGU-Ks, with both having previously used two, but it is understood that these are actually the same specification as before.

Vettel was the fastest of the Ferrari drivers in Friday practice, ending up six tenths of a second adrift of Nico Rosberg. But he believed there remained the chance of a good performance.

"Always, I think every race is an opportunity," he said. "I think we had a decent day, but not entirely clear where we are because we didn't have much running in the afternoon in particular. Overall we should be OK."

Additional reporting by Roberto Chinchero

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