Lewis Hamilton led a McLaren one-two ahead of team-mate Jenson Button by setting the fastest lap in a rain-interrupted second session of free practice for this weekend's Australian Grand Prix.
While the first practice session had been held during bright sunshine, clouds had gathered as the afternoon progressed and by the time the cars took to the circuit once again rain had started to fall intermittently.
But Hamilton got the better of the conditions to produce the fastest lap of the day with a time of one minute 25.801 seconds that put him ahead of reigning world champion Button by 0.275secs.
Red Bull's Mark Webber - hoping to secure a maiden win at his home race this weekend - was third with a time of 1:26.248, while seven-time world champion Michael Schumacher recovered from early problems in the session to vault up to fourth from 20th in his Mercedes.
Vitaly Petrov produced an impressive display to go fifth fastest in his Renault, while Toro Rosso's Sebastien Buemi was sixth with the Force Indias of Adrian Sutil and Tonio Liuzzi seventh and eighth respectively.
Rubens Barrichello of Williams and Nico Rosberg - who was beaten in practice by Mercedes team-mate Schumacher for the first time this season - rounded out the top 10.
Sebastian Vettel, who started on pole at the season-opener in Bahrain, finished 16th after going into the gravel at one point in his Red Bull.