Testing kicked off at Barcelona today, with sixteen drivers in action representing nine teams, as F1 action returned after a break of almost six weeks.

Following the (early) departure of Michelin, all the teams are now running on Bridgestone, and consequently it was a question of 'softly, softly' for the teams that previously ran on French rubber, though McLaren's Pedro de la Rosa posted the second fastest time of the day. BMW and Honda also appear to have made a smooth transition to Japanese rubber.

Felipe Massa and Luca Badoer were on duty for Ferrari, the Italian team's successful relationship with Bridgestone continuing as the pair finished first and third. The Maranello outfit's technical programme featured long run tests, experimentation with new components and working on the set-up of the 248 F1.

McLaren had Lewis Hamilton and Pedro de la Rosa on duty. Both drivers were working on initial evaluation of the Bridgestone Potenza tyres and their affect on the balance of the car. In addition front wing, rear wing and floor packages were also assessed.

In the morning session Lewis stopped out on track with a minor engine mapping issue, however there was no problem with the engine and he was able to resume running once he returned to the garage.

BMW was represented by Nick Heidfeld and Robert Kubica. The morning was cold with the team opting not to send the Pole out at the beginning of the day, hoping for warmer temperatures as his main focus was the new Bridgestone tyres.

Heidfeld worked on a new transmission and was the first of the two drivers to go out on the track in the morning. Kubica was also testing new parts for the 2007 car.

Tomorrow, Nick will continue with the transmission testing and also work on brakes. The work of adjusting to the Bridgestone tyres will also continue on both cars, while Robert will also work on mechanical components for the 2007 car.

Rubens Barrichello and James Rossiter began work for Honda. Both drivers concentrated on initial tyre evaluations alongside a programme of set-up changes. Christian Klien will have his first run in a Honda car tomorrow (Wednesday) as he takes over from Rossiter.

Not for the first time, WilliamsF1 had just one driver on duty, this time Alexander Wurz. The Austrian finished ninth quickest, albeit 1.57s off the pace, once again using the Toyota powerplant.

Renault had Heikki Kovalainen and Nelson Piquet on duty. For the World Champions, the objectives for the week are to learn as much as possible about the Bridgestone tyres and to give the drivers the opportunity to adapt their driving to them.

The latest testing agreement also provides for a reduction in the number of tyres used by the teams during testing, to avoid the need for Bridgestone to manufacture and transport excessive quantities of tyres. Both drivers therefore had access to three sets of tyres each for their running today.

This first test since the team's double championship victory will also be used to complete reliability running on new components to be used in 2007.

Kovalainen began preparations for his Grand Prix debut next March in Melbourne in diligent fashion. He completed a substantial 91-lap programme without any problems, setting a fastest lap of 1:19.188. As for Piquet, he continued to learn about the team and the car while running the first laps with the new 2007 gearbox in a 'hybrid' R26 chassis.