MELBOURNE (AFP) - Lewis Hamilton and Nico Rosberg showed that Mercedes could be the team to beat at the season-opening Australian Grand Prix when they impressively topped the time sheets in practice on Friday.

With teams adapting to a raft of technical changes in Formula One, Hamilton overcame mechanical problems in the first session to time quickest in the second run-out ahead of his team-mate.

Ferrari's Fernando Alonso was third fastest, while four-time defending world champion Sebastian Vettel, who endured severe problems in pre-season testing, placed an encouraging fourth.

"I'm satisfied with P2 (second practice). P1 I obviously didn't get anywhere," said Hamilton, the 2008 world champion.

Hamilton and Rosberg have been tipped to fight it out in Sunday's race, given Mercedes' superior pre-season testing and adjustment to the technical changes, which also include a fuel limit.

Hamilton put in a scorching lap on soft tyres to post a best time of 1min 29.625sec, 0.157sec ahead of German team-mate Rosberg (1:29.782).

The Mercedes duo were the only drivers to go below 1:30, demonstrating an early edge over the rest of the field ahead of Saturday's qualifying for grid positions.