(CNN) -- Rubens Barrichello in the Brawn GP produced the fastest time of the week in Formula One testing in Barcelona as world champion Lewis Hamilton struggled to keep pace in his new McLaren.
Hamilton tests drives the new McLaren at the Circuit de Catalunya.
Barrichello's performance on Friday at the Circuit de Catalunya capped a remarkable week for the Ross Brawn-led team which has emerged from the ashes of the old Honda outfit.
His teammate Jenson Button was over a second quicker than his rivals on Thursday, while veteran Brazilian Barrichello became the only driver to dip under 79 seconds late on the final day of testing.
The Brawn GP car was almost certainly set up in qualifying trim, but was significantly quicker than Hamilton's best time of one minute 20.869 seconds.
Barrichello set his fastest timing of one minute 18.926 seconds towards the end of a 110-lap stint at the Spanish circuit.
Williams' Nico Rosberg was 0.848secs adrift, with Timo Glock in his Toyota just over a second down.
Sebastian Vettel (Red Bull Racing) and two-time world champion Fernando Alonso (Renault) finished fourth and fifth overall.
Ferrari's Felipe Massa, Robert Kubica of BMW Sauber and Hamilton, who all challenged for the world title last season, were sixth, seventh and eighth respectively.
Hamilton was almost five kilometres an hour down on Barrichello, completing just 70 laps, but produced the best time of the week for McLaren by nearly a second.
The British star and his Finnish teammate Heikki Kovalainen will head to Jerez nest week for a final testing session ahead of the season-opening Australian Grand Prix on March 29.
Earlier this week, team chief Ron Dennis said he was unworried by their slow pace in testing and claimed they would be world title contenders again.
"The objective is to go to Australia and be the most competitive car there, not to come out of every single test at the top of the timesheets," he told BBC Sport.
"Testing is about a disciplined approach to making the car go faster and you have to ignore the performance of the other teams."