Martin Whitmarsh admitted overnight that the McLaren team had been thwarted in its attempts to use Friday free practice to continue the development of its MP4-25 ahead of the Belgian Grand Prix, but insisted that it would maintain its pursuit of the performance it needs to close in on rival Red Bull Racing.

Although erstwhile championship leader Lewis Hamilton finished the day third overall on the timesheets, the changing - and often inclement - weather conditions in the Ardennes prevented any meaningful comparative running, leaving the team hoping that it can trip over the secret to getting the best from its new 'blown diffuser' system.

"Obviously, we know the raw material, we know the data and then we have expectations in terms of corner speed etc, but we weren't achieving those in Hungary and I think we needed to have a look at that, understand it and try and get that performance out of it," Whitmarsh commented.

"It's too early to say. Today has been an 'interesting' day, but a frustrating day, I am sure, for all of us. To do the engineering development programme that you try and do on Fridays, when the conditions are this changeable, is almost impossible - and, certainly, to do it quickly. There is a lot of instrumentation on all of our cars, so I am sure most of the teams ran different components, different systems, on their car today, but most of them couldn't tell you if they have made any progress until they have gone into the detail as, clearly, the track was evolving one way or the other according to the weather conditions.

"But, overall, I am convinced that we can do a better job than certainly we appeared to do in Hungary, and we will see as the weekend goes on."

Whitmarsh also dismissed speculation that the team was considering ditching its F-duct system, both this weekend and at the Italian Grand Prix in a fortnight's time.

"I think you will find we will use it here - it is on the car, it is running," he confirmed, "I have not heard that conflicting statement. I have heard some statements about Monza, but I don't see, personally, any merit in us declaring what we are going to do to our competitors before we get there."

Being in the thick of the title fight ensures that McLaren's focus remains firmly on developing the MP4-25 between now and the Abu Dhabi finale in November, but Whitmarsh revealed that the team's resources had also allowed it to begin work on its 2011 challenger.

"We are still working hard on this year's car as there is still a good championship ahead and we are pushing hard," he confirmed, "Inevitably, you have got to have your mind on next year as well, but we are certainly pushing hard on this year's car.

"There is a lot of effort to bring performance improvements here and to continue bringing them for the rest of the year, but there is a team working on next year's car as, in reality, you have R&D programmes which, hopefully, are going to come to fruition and the resources gradually build."