McLaren put a disappointing winter testing programme behind them to take a surprise one-two in second practice for the Australian Grand Prix.
Brits Jenson Button and Lewis Hamilton topped the timesheets in second practice at Albert Park ahead of the dangerous Fernando Alonso in third.
First practice followed the winter testing trend with McLaren off the pace finishing down in sixth and seven, over a second behind the impressive Red Bulls.
Pre-race favourites Red Bull secured first practice with the two quickest times from Mark Webber and Sebastian Vettel respectively with Alonso perched in the third in the Ferrari again ready to launch an attack.
But second practice was the turning point for McLaren as they set the two fastest lap times which has left everyone in the paddock scratching their heads.
You cannot read too much into the times in practice as fuel amounts are unknown but McLaren, with free use of the Adjustable Rear Wing, will be a threat this season after all.
A new front wing and complete re-design of the exhaust system by the McLaren boffins since their last poor testing performance has worked wonders as Button posted a time three tenths quicker than defending champion Vettel.
Elsewhere, Michael Schumacher made an impressive start to the new season and showed there is life in the seven time world champion yet finishing sixth having run top for most of the session.
Given the right car, the experienced German could well spring a shock and with Nico Rosberg showing potential again, Mercedes GP will be looking for a first win later in the year.
For the rookies at their first Grand Prix, Sauber driver Sergio Perez clocked the quickest time in an impressive eighth position but was still over a second off the overall pace.
Paul Di Resta, Pastor Maldonado and Jerome D'Ambrosio complete the rookie field and made up the second half of the timesheet but will have learned so much from their first involvement in a F1 race weekend.
There is also worrying news for Hispania who completed a couple of installation laps but never clocked a time. There are concerns as to whether team, in its second year, will make the race on Sunday having had such little running time.
Coverage of third practice kicks off at 0125 GMT and qualifying is on at 0600 GMT on Saturday.