Renault's Fernando Alonso knocked the Brawn team off the top of the timesheets in F1's final week of pre-season testing in Spain on Monday while McLaren continued to struggle.
Spain's double world champion, who had crashed his R29 car on Sunday's first day of testing, completed 103 laps of the southern Jerez circuit with a best time of one minute 18.343 seconds.
Brazilian Rubens Barrichello, driving the former Honda car renamed as Brawn GP after new owner Ross Brawn, lapped in 1:18.398 with British teammate Jenson Button third fastest in 1:18.892 on a hot afternoon.
"I'm happy with the day as we did more than 100 laps which was our target for my final day of winter testing," Alonso said in a team statement.
"This has been the first time we have run on a really hot track and the information we have from today will be very useful for the first few races, which are usually very hot.
"We are really well prepared for the new season," he added. "We can go to Australia knowing we have maximized the time we had available."
The season starts in Melbourne on March 29, with Malaysia the weekend after that.
Barrichello, fastest on Sunday, drove the Brawn on Monday morning before handing over to Button, who was halted by a gearbox problem after 12 laps in the afternoon.
McLaren's world champion Lewis Hamilton, whose team recognized last week they were having problems with the new car's lack of pace, completed 87 laps with a best time of 1:19.513.
The Briton, who was evaluating new aerodynamic modifications, was fourth of the five drivers on the track.
The testing at the circuit wraps up on Thursday.
Best Jerez times:
Fernando Alonso (ESP/Renault) 1:18.343 (103 laps)
Rubens Barrichello (BRA/Brawn) 1:18.398 (62)
Jenson Button (GBR/Brawn) 1:18.892 (12)
Lewis Hamilton (GBR/McLaren) 1:19.513 (87)
Nico Rosberg (GER/Williams) 1:19.783 (123)
(Reuters via China Daily March 18, 2009)
