The team has yet to get the most of of their 2004 chassis the FW26, but Theissen explained in an interview for Eurosport that it was a risk that the team was prepared to take to challenge Ferrari.

Theissen said: "Williams took a big risk with a very different car concept this year, which we certainly supported because if you want to catch up, and not only catch up the front-runner but overtake him, you have to take a risk.

"If you do everything like the top guys, you can only close in but not pass. So that was a clear decision supporter by us to take the risk. Unfortunately, it didn't pay off."

Theissen added that despite the difficult start to the season the team was moving forward and was looking to achieving some good results in the final series of races.

He added: "We had a very difficult first part of the season. I think we are gaining ground and we are going back slowly but steadily. That's what any kind of sport is about.

"You have strong phases when everything goes on itself then you have difficult times and have to fight. Williams and BMW are fighting as a team. We'll see several improvements over the final six races and I really think we can close in.

"Certainly we made some mistakes as a team, and we were sometimes unlucky as a team. You have to understand if you fight and try to catch up you take a bigger risk as usual. If you refer to the brake problems in Barcelona, it was a situation like this. We were trying to make the car as competitive as possible."

"On race day we went a bit over the top. That was, looking back, certainly a wrong decision but if you try to squeeze out all the capabilities the car has it sometimes happen."

As for the arrival for Mark Webber in the team for 2005 Theissen spoke of how is was looking forward to his arrival.

He said: "I'm really looking forward having Mark in the team. Mark has proven that he is fast. I think he is well structured. He's working very well and very hard with his engineers and mechanics. I think he can be a very good team with his engineers. I'm very confident. He will be strong with us."

As for Webbers team-mate Theissen made it clear that there was not a requirement from BMW to have a German driver.

He said: "The first priority is to have the two fastest drivers possible in the cars. Only then you can explore the marketing side. So that is absolutely clear. We don't need a German driver.

"BMW is a global corporation, Formula One is a global business and nationality of a driver only plays a role in one of 17 or 18 countries we go to. So that makes clear that it cannot be the top priority. Performance is always the top priority."