Ex-Honda driver Jenson Button has put the new Brawn GP Formula One team on top of the testing timesheets in Barcelona, as World Champion Lewis Hamilton struggled.
The Brit was more than a second faster than the next quickest driver, Ferrari's Brazilian Felipe Massa.
Button says it was pleasing to achieve a full day's running without any issues, considering the challenges the team has faced in the past couple of months.
The fledgling F1 team only secured their future last week after a management buyout led by new principal owner Ross Brawn.
Honda announced in December that they were pulling out due to the credit crunch.
It wasn't such a good day for Lewis Hamilton however, who finished bottom of the timings after 86 laps.