It may only be three weeks since the Brawn GP BGP 001 first took to the test track at Silverstone, but both Jenson Button and Rubens Barrichello featured right up at the sharp end of proceedings in practice for this weekend's curtain-raising Australian Grand Prix - and the British star reckons the speed shown so far is only the tip of the iceberg.

Having risen from the ashes of what was Honda F1, Brawn GP was expected by most paddock sages to be lucky to make the starting grid Down Under at all after such an uncertain winter and late start - and if it did, they surmised, then it would do well to drag itself away from the back of the pack.

When the new Mercedes-powered machine subsequently went on to stun observers in testing - regularly lapping up to a second a lap quicker than any of its rivals - cynics suggested it was merely an artificial ploy in an effort to attract sponsors and that the true acid test in Melbourne would expose the team's winter games. With both cars remaining firmly inside the top six in practice, however, the bubble is showing no signs of bursting yet a while.

"To be here in Melbourne is a real achievement for the team," enthused Barrichello, fourth-fastest in the morning and second in the afternoon, barely a tenth of a second shy of Williams' pace-setting Nico Rosberg. "It feels good to be back in the car and working towards a race weekend strategy again.

"Despite the limited testing time that we were able to do before this race, we have proved that we have a competitive car and we achieved some good work today. We evaluated both tyres and are happy with the overall performance, so I think we have a good chance of a strong qualifying performance tomorrow."

Both the Brazilian and team-mate Button are sporting helmets liveried in Brawn GP's distinctive new yellow, black and white colour scheme to mark the occasion. The latter wound up just over two tenths adrift of the sister car, similarly scrabbling around for grip on Albert Park's public roads but joining in with a thorough evaluation of the Bridgestone tyre compounds available for the race later in the afternoon.

"It was great to finally get the season underway today," the former Hungarian Grand Prix winner underlined. "We had a good first day of practice and the long-run performance looks competitive, particularly on the harder tyre. We still have some work to do on the softer tyre, so that will be a priority for tomorrow's practice session.

"I had traffic on both of my new tyres runs at the end of the day which was a shame, so we don't know how quick we are over one lap yet - but there is plenty of time to find that out tomorrow."

"The circuit at Albert Park is very different to the tracks that we used for our limited pre-season testing programme," added team owner Ross Brawn, "so our focus today has been on setting the car up to suit the conditions that we have here and the preferences of our drivers.

"Track conditions improved considerably in the second session; however, we are clearly not alone in finding the experience of running slightly later in the day less favourable than anticipated. It is a useful indication of what we may find when the race runs at a similar time on Sunday.

"The car performed well and we are pleased with the day's work, experiencing only minor issues which are to be expected with our limited testing mileage. A good start to the weekend."