From appearing to be midfield contenders at best in pre-season testing, McLaren team-mates Jenson Button and Lewis Hamilton ended day one of the Australian Grand Prix at the top of the timesheets.

While Friday's performances are notoriously hard to quantify as teams work on their own preparation, McLaren's result is vindication for the hard work put in between the final Barcelona test and the start of action in Melbourne that has seen both MP4-26s fitted with a heavily revised exhaust and underbody in an effort to claw back the deficit to expected rivals Red Bull and Ferrari.

According to German publication Auto Motor und Sport, the new layout mimics that of the former's RB7 rather than seeing McLaren revert to a more conventional system, and the decision could still take the Woking team time to perfect, but team principal Martin Whitmarsh is optimistic that it may have unlocked the potential that Button spoke of at times during testing.

"I decided that we should focus for the start of the season on a solution that will definitely work," Whitmarsh was quoted as saying before the weekend began, and his optimism remained after watching his two drivers move to head of the field in the afternoon session at Albert Park.

"Today was a good, solid day," he reported, "Both our drivers performed very well, and we got a lot of work done. The Pirelli tyres exceeded expectations in terms of reliability, and we were thereby able to complete some good long runs and collate plenty of useful data and info. We ran a brand-new floor and a brand-new exhaust today, and it's always nice to bring new parts to a circuit and see them deliver what you'd expected. Today we saw a decent correlation from simulator to racetrack.

"Although it's always pleasing to see your cars finish first and second in any session, we won't be counting our chickens before they're hatched - you don't get any points on Fridays. All I'll say now is that today was an encouraging day, we're going in the right direction, and we're hoping to continue in that direction in our efforts to strive to find further improvements overnight."

Button and Hamilton had been at the sharp end of proceedings in session one before late laps elsewhere pushed them back to sixth and seventh respectively, and the 2009 world champion - who has won the past two Australian GPs - was suitably encouraged by the day's performance.

"Today showed that, first of all, we've got reliability - which is great," he noted, "That's something we've not had all winter, so to have a car that runs for as many laps as we want it to is very satisfying. It also means we can get stuck into our set-up work and improve the car.

"I don't think there's much to be gained from looking at today's times, so I'm not going to get too carried away, [but], still, it's been a positive day because we've been able to do so much running and get a good feeling for the car on different fuel-loads. I'm so happy with how hard the guys have worked and what they've brought to this race - they've worked really hard and they've delivered something good here. The new exhaust has definitely brought performance to the car - it feels much better and makes the handling more 'complete'. When you have downforce at the rear, you can also add it at the front, and then you put temperature in the tyres - there's so much that comes with downforce."