With rain looming, so too is Formula One’s rainmaker at the Australian Formula One Grand Prix.

The sport’s current benchmark Sebastian Vettel signalled his intent for a world drivers’ championship four-peat with a sensational practice showing on Friday for Sunday’s season-opening race.

Unsettled weather conditions predicted for the weekend could well liven up Saturday qualifying at Albert Park.

But they’ll need to if Vettel and Red Bull teammate Mark Webber are to be shaken down from the lofty heights they reached in the season’s first two practice sessions.

Both were head and shoulders above their rivals despite Webber having a late spin in session two – the McLarens of Jenson Button and Sergio Perez struggling noticeably for pace.

Vettel and Webber’s practice one-two was the first indication of the team’s speed after topsy-turvy results from Barcelona during pre-season testing.

Vettel believes more performance could be squeezed from the car, though he and Webber are mindful that rain predicted for Saturday could mix up the grid.

“There’ll be a lot of decisions when we’re running on circuit over the next few days, that’s for sure,” Webber said.

“We need to get as many of those right to get the maximum result,.”

Webber is aiming to better his best result at his home GP – last year’s fourth place.

The other Australian driver, Daniel Ricciardo, was 14th fastest of the 22 drivers in Friday practice.

But if he wants to repeat his top 10 home finish from last year, the West Australian knows his Toro Rosso must urgently find extra speed.

“There is more to do overnight to find more pace,” he said.

“It’s nice to be racing at home in Australia again, which is an added incentive to work really hard to get the car to go quicker and give the fans something to cheer about on Sunday.”