Britain's Jenson Button has put Brawn GP back on top of the timesheets in the Formula One team's final pre-season test while McLaren and world champion Lewis Hamilton continued to struggle.
While Button signed off with 114 laps of Spain's Jerez circuit and a best time of one minute 17.844 seconds Hamilton did 121 laps but was the slowest of the four drivers on the track at Jerez in 1:19.121.
The first race is in Australia on March 29.
McLaren have already conceded their car is not quick enough to win races yet and they say strong, gusty winds hampered efforts to evaluate a series of small aerodynamic modifications.
Hamilton, Formula One's youngest champion, has now completed his pre-season testing and will hand over to team mate Heikki Kovalainen for the remaining two days.
