Red Bull's Mark Webber swept to the fastest time in the first practice session of the new Formula One season at the Australian Grand Prix on Friday.

Webber, hoping to become the first Australian to win his home grand prix on Sunday, clocked one minute 26.831 seconds on the last of his 20 laps to edge his world champion team mate Sebastian Vettel by 0.327 seconds.

Spain's Fernando Alonso, runner up in the title race last year, was third quickest for Ferrari in 1.27.749 ahead of Germany's Nico Rosberg, who confirmed Mercedes' strong showing in pre-season testing with the fourth fastest time (1.28.152).

Experienced Brazilian Rubens Barrichelo, a winner here with Ferrari in 2002, sprung the surprise of the session with the fifth quickest time for Williams ahead of the McLarens of Jenson Button and Lewis Hamilton.

The duo of British former world champions made the most of the time available to them after reliability problems disrupted their pre-season testing and forced McLaren to rejig their car this week.

Button was the quicker of the pair over his 29 laps with Hamilton seventh fastest after running 26 laps, edging seven-times world champion Michael Schumacher into eighth place on the timesheets in his Mercedes.

Venezuelan Pastor Maldonado was the quickest of the new drivers with the 15th best time in the second Williams car.

Both Ferraris carried the Japanese flag on the front of the car along with the message "Don't give up Japan" in a reminder of the deadly earthquake and tsunami that has devastated the country.

Felipe Massa could have done with some encouragement himself after leaving the track twice in a poor session where he registered the 11th fastest time in a car that is expected to challenge for the title this season.

After a two-week delay caused by the postponement of the Bahrain round of the championship because of civil unrest in the Gulf kingdom, the 12 teams finally got the season underway in earnest under leaden skies at Albert Park.

More rain is forecast for Saturday but the skies are expected to clear for race day on Sunday.