MELBOURNE: Lewis Hamilton and Jenson Button put McLaren-Mercedes in good shape ahead of qualifying for the Australian Grand Prix with the fastest times in Friday's practice.

Hamilton, who won the Australian race two years ago on the way to claiming the world title, clocked the quickest lap time of one minute 25.801 seconds in the second session, thrown into disarray by light rain. Hamilton, who was third in the season-opening Bahrain GP, was 0.275sec ahead of his teammate and reigning world champion Button, whose best effort was 1:26.076.

Button believed he could have trumped his teammate's time had he not been held up by Sauber driver Pedro de la Rosa while on a flying lap late in the second session. Team principal Martin Whitmarsh cautioned against taking too much out of the first two practice sessions ahead of Sunday's Australian race. "We've had a reasonable day today, but it's only Friday and it's pretty impossible to know exactly where you are, you've just got to follow your own programme," Whitmarsh said.

The race grid positions will be decided in Saturday's qualifying. The McLarens held a sizeable advantage over their nearest rivals, Red Bull-Renault's Mark Webber and seven-time world champion Michael Schumacher, making a comeback to F1 in a Mercedes after three years off the circuit.

Webber, bidding to win his home GP at the ninth attempt, was third fastest in 1:26.248, some 0.447secs down on Hamilton's chart-topping time. Schumacher, who is chasing his fifth Australian race victory this weekend, was fourth best in 1:26.511, 0.710sec adrift of Hamilton. "My first session was a bit handicapped by red flags, later we faced some rain in the second session," Schumacher said. "But we learned a lot and we could improve the set up of our car quite reasonably. In the end our times were competitive so I think we can look forward to the rest of the weekend."

It was a frustrating practice session for the other main race contenders with Ferrari's Spanish two-time world champion Fernando Alonso down in 15th position with 1:29.025 and 3.224secs behind the best time. Alonso won the Bahrain GP on his Ferrari debut a fortnight ago.

Red Bull-Renault's Sebastian Vettel of Germany was 16th in 1:29.134 in practice and Ferrari's Felipe Massa 17th in 1:29.591. "I had a drift off the track at the end of the second session," Vettel said. "It was my mistake and it meant I missed the most important time on the track at the end of P2. But the car feels good and Mark (Webber) showed that we are right there. It looks very close between the top cars."