Takuma Sato struggled through the sweltering heat that gripped Jerez today, to post the fastest time of the day.

At one stage, the ambient temperature hit 40 degrees C, causing team personnel to visibly wilt under the extreme conditions.

Sato was on duty for the Brackley outfit, along with teammate Jenson Button, who was taking over from Anthony Davidson. The Japanese driver completed 79 laps in the intense heat, posting the best time of the day, before experiencing a gearbox problem which left him sidelined for the rest of the day. Button also had transmission problems, and consequently only managed to complete 42 laps, posting the fourth fastest time of the day.

Kimi Raikkonen was impressive in the McLaren MP4-19B, the Finn completing 121 laps and posting a best time just 0.250s off Sato's best. This was the first day of testing for Kimi, who previously ran the MP4-19B at Silverstone. He had only just returned from America and complained of feeling "tired". Also on duty for the Woking outfit was David Coulthard. The Scot, running a different set-up to the Finn, completed 93 laps and posted a best time 0.8s slower than his teammate.

Marc Gene continued his tyre evaluation programme for the French GP, completing more than a race distance, though it's still unclear if he will replace Ralf Schumacher. Meanwhile, Antonio Pizzonia completed 47 laps, as he focused on testing new traction control components for the forthcoming European races.

Propping up the timesheets were the two Toyotas of Cristiano da Matta and Ryan Briscoe. The Brazilian, like Kimi Raikkonen, found the heat oppressive, and constantly complained of feeling tired.

Times