A cold start to the day, followed by afternoon rain and a subsequent drop in temperatures, hit today's first day of testing at Barcelona, meaning that the only valid running was in the late morning, when conditions were almost ideal.

On the day that the all-white Super Aguri SA05 - formerly known as the Arrows A23 - attracted much of the media attention, it was WilliamsF1's Mark Webber who set the pace, with Kimi Raikkonen hot on his heels.

It wasn't all plain sailing for Webber, the Australian stopping on track in the morning following a mechanical failure. However, it was even worse for teammate Nico Rosberg, who, having spent much of the morning making practice starts - and consequently single lap runs - subsequently suffered an engine failure. In the afternoon, his running, like that of his rivals, was severely restricted by the weather conditions.

The programme for the week is focused on continuing long runs and set-up work. Today's session saw Kimi cover 270km over the course of 59 laps, during the morning he completed two 20-lap runs, evaluating different Michelin tyres on each run.

Team-mate Juan Pablo completed over 100kms in his MP4-21. The Colombia had a transmission issue early in the afternoon, which the team were working on rectifying, however the decision was taken to end his running for the day early due to a heavy fall of rain shortly afterwards.

With wet track conditions, technical feedback from running is limited and as the drizzle continued for the remainder of the day, Kimi ventured out of the garage only on a couple of occasions to complete some practise launches in the damp conditions.

Third quickest was Robert Doornbos in the Red Bull, the Austrian team clearly frustrated by the weather.

"We lost track time," said Chief Test Engineer, Ian Morgan, "but it did not really affect our programme, as putting distance on the car was more of a priority than development today.

"As we have done quite a bit of running in the wet already, we decided it was not really worth going out," he added, referring to conditions in the afternoon. "Although we did do a couple of laps at the end of the day, just to check some new software."

Tiago Monteiro was Midland's sole representative, the Portuguese driver matching Raikkonen in terms of most laps completed (59).

Despite the weather, the team continued making good progress with some race simulation work, general reliability improvements, and control systems testing. Tiago will drive again tomorrow morning to undertake some tyre development work before handing over the car to Christijan Albers for the remainder of the test.

"We had some really promising runs with the car this morning, which was encouraging, as I believe we ended up just over one second behind the quickest time of the day," said Monteiro. "We were preparing to begin practicing race simulations in the afternoon but unfortunately, it started to rain heavily on the out lap and we held off for a while, but finally called it a day when the rain showed no sign of letting up. In the end, we did about 60 laps - which is very close to a race distance - without any problems. The car's reliability is excellent and our pace is improving, so I am very pleased with the day's performance."