Melbourne - Williams upstaged the favourites Friday in the first official Formula One practice session of 2009.

German Nico Rosenberg, third in Melbourne last year, topped the time sheets ahead of Sunday's Australian Grand Prix.

Team-mate Kazuki Nakajima was second in the first free practice of the day. Former world champion Kimi Raikkonen was in third place for Ferrari, followed by the first Brawn GP driven by Brazilian veteran Rubens Barrichello.

Pre-race favourite Jenson Button's Brawn GP car was sixth-fastest, while defending world champion Lewis Hamilton was 16th-fastest.

The time tables might change in the second practice session later in the day. (dpa)