WilliamsF1's Nico Rosberg was the quickest of eleven drivers on duty at the Circuit Ricardo Tormo, Valencia, today.

On Tuesday it was Mark Webber who set the pace, today it was teammate Rosberg's turn, as the Grove outfit continues to show promising pre-season form.

"It was a good day for testing with an air temperature of 21 degrees and track temperature of 28," said Sam Michael. "This puts us close to some of the early GP's in terms of getting the tyre compounds in the correct window for Bridgestone.

"Nico spent the day on long runs for reliability and testing tyres. Mark was testing some new brake components that are interesting. Unfortunately he had to stop earlier than planned."

Tomorrow (Thursday), Alexander Wurz joins Nico for the final day of the test.

Kimi Raikkonen's programme, on his first day of testing, was set-up work, with the Finn putting in a time of 1:11.199. A minor transmission problem in the morning meant that the Kimi didn't take to the track for the first time until shortly before 11:00.

Juan Pablo Montoya spent the majority of the morning completing a race distance in his MP4-21, which included pit stop practice for the team. The Colombian's afternoon saw work focus on set-up programmes for the opening races over shorter runs.

Towards the end of the session both Kimi and Juan Pablo had mechanical failures on track. Kimi returned to the track for the final 10 minutes, whilst Juan Pablo's day ended as the team prepared his car for tomorrow's running.

Both drivers will continue testing in the two MP4-21s tomorrow.

Renault began its three-day programme with Giancarlo Fisichella and Heikki Kovalainen, both at the wheel of the new R26.

Heikki completed a race simulation during the morning in order to reach maximum mileage with his engine, before the planned change of the V8 unit. On the other side of the garage, Giancarlo Fisichella worked on set-up evaluation and tyre development with Michelin. He was delayed by several small problems this afternoon, but was nevertheless able to complete useful work on his programmes.

"I had a few problems today which meant I didn't do as many laps as I wanted to," said the Italian. "Nevertheless, we are still on the right track. We are running to get miles on the car at the moment, not to set impressive times. I am still feeling very confident with the R26."

"I had a very good day," added the Finn. "I managed a race distance this morning, before doing some brake development in the afternoon. We focused on doing long runs, and the times make me think we are competitive again at this track. We are making progress every day, and the car seems reliable. I am happy."

"Heikki enjoyed a very good morning, and completed a race simulation without any problems," said Christian Silk. "We then changed his engine, and completed a short brake programme this afternoon. Giancarlo had a more difficult time, with several small problems holding him up, and red flags interrupting his runs. In spite of this, we had a good day overall, and once again managed to do plenty of laps."

David Coulthard, Christian Klien and Robert Doornbos were on duty for Red Bull Racing.

Christian continued to drive the 02 chassis, featuring the latest aerodynamic configuration. The Austrian did more chassis set-up work, as well as testing control systems and evaluating tyres for the Bahrain and Malaysian Grands Prix.

Robert Doornbos, in the older 01 chassis, also worked on set-up and control systems, running in the morning before handing over to David Coulthard.

"This gives David a good reference for comparison when he drives RB2-02 tomorrow," explained Technical Director, Mark Smith. "Apart from a couple of stoppages with Christian's car, this has been another productive day."

Coulthard tries chassis 02 for the first time tomorrow and will be the only Red Bull driver on track, as the other car is being shipped back to the factory to be fitted with the latest bodywork package.