Driver battle goes on as Williams kick off 2005.

The BMW Williams F1 Team has started its 2005 season campaign early after launching its livery, 2005 driver line-up evaluations and a host of new commercial alliances in Bahrain.

Following the announcement of a number of new sponsors over the past few days, the team has now confirmed that Antonio Pizzonia and Nick Heidfeld will continue their driver evaluations over the course of three tests in Spain during January before a decision is finally taken on the identity of the team's second race driver.

The new teammate to Mark Webber for the 2005 season will then be presented at the team's car launch on 31 January in Valencia.

Pizzonia had looked like the man most likely to partner Webber after it became apparent that Jenson Button would be staying with BAR for at least one more year.

However, engine suppliers BMW are believed to favour German driver Heidfeld, with it the ongoing test sessions being used to decide who will fill the second race seat for the upcoming season.

While Pizzonia said he would be prepared to fill a testing role again in 2005, he admitted that he wants to be able to race.

"For sure, I want to race in 2005," he said. "The evaluation at the tests is fine, tough competition is just a natural part of Formula One. This month is going to become the most important of my career. If I don't get the second race seat, I will give the team every support to win races again as a test driver."

Rival Heidfeld, long linked with a top F1 seat, admitted that the battle to secure the vacant seat was the biggest chance of his career, and he will hope to come out on top in order to take his place on the grid when the season starts in Melbourne.

"Appearing in full team gear for the very first time has been really cool," he said. "I am very happy to be part of the team. Fighting for the second race seat is the biggest chance I have ever had in my career. Whether at a test or in the factory, being with the BMW Williams F1 Team is a complete change to what I'm used to. I am impressed by the professionalism, the resources and the determination of the crew. I had a warm welcome and felt immediately at home."

No matter what the outcome of the decisive tests, both drivers will have a role with the team in 2005, with Williams confirming that whichever driver isn't selected for the race seat will take the test driver role.

With the new team livery unveiled at the Bahrain International Circuit yesterday, all three drivers entertained spectators from across the region to a demonstration at the desert venue.

Webber admitted that he was delighted to be part of the team and was looking forward to the official launch of the car at the end of the month.

"Apart from having enjoyed the last two action packed days here in Bahrain a lot, I am the happiest man in the world to be a member of the BMW WilliamsF1 Team," he said. "I am already very pleased with the work that has been done during pre-Christmas testing. Everybody in the team is working night and day because we want to win. Apart from the test sessions, preparation work for the launch of the FW27 at the end of the month is running flat out."