Renault's Fernando Alonso knocked the Brawn team off the top of the timesheets in Formula One's final week of pre-season testing in Spain.
Spain's double world champion, who had crashed his R29 car in yesterday's first day of testing, completed 103 laps of the southern Jerez circuit with a best time ahead of Brazilian Rubens Barrichello, driving the former Honda car renamed as Brawn GP after new owner Ross Brawn.
British team mate Jenson Button was third fastest.
The season starts in Melbourne on March 29th, with Malaysia the weekend after that.
McLaren's world champion Lewis Hamilton, whose team recognised last week they were having problems with the new car's lack of pace, completed 87 laps with a best time a second slower than Alonso.
The Briton, who was evaluating new aerodynamic modifications, was fourth of the five drivers on the track.