Jenson Button and Lewis Hamilton showered lavish praise on their McLaren team for conjuring a "massive" improvement in their cars to allow the pair to set the quickest times on the first day of practice at the Australian Grand Prix.
The 2009 world champion Button had hoped for a pleasant surprise following a winter testing plagued with reliability problems, and got his wish with a time of one minute 25.854 seconds in the second session, the fastest for the day.
Fellow Briton Hamilton, the 2008 world champion, was 0.132 seconds behind with Ferrari's Fernando Alonso third quickest for Ferrari and world champion Sebastian Vettel fourth for Red Bull.