The AT&T Williams F1 team haven't done a good enough job in 2008 and need to do a lot better next season, that's the frank assessment of technical director Sam Michael ahead of the season finale in Brazil next weekend.

Williams finished fourth in the constructors' championship in 2007, yet this year the team is currently only eighth - and while Red Bull Racing are only three points in front going into the final event at Interlagos, the squad has slipped behind the likes of Toyota and Toro Rosso.

Speaking exclusively to Radio recently Michael added that they definitely need to correct that in 2009.

"This season has not gone as well as planned. F1 is competitive throughout the grid, but regardless of that as a team we haven't done a good enough job," he stated. "We didn't plan to drop from fourth in the constructors' and we must correct that now.

"I think the main thing for 2009 is to do better than this year. We want to at least get back towards the top pack."

Asked why they have slipped back, Michael picked out two reasons: "Firstly all the teams have had ups and downs in terms of performance - regardless of where they are on the grid," he explained.

"The difference with Williams is that we have failed to score points at the tracks where we are strong - places like Monaco and Montreal - and it doesn't take much to see that those points would have made a significant difference to the outcome in the constructors' table.

"We probably wouldn't have been in a position where we could finish fourth but we would have been higher up than where we are at the moment.

"Secondly we have devoted a lot of resources towards the 2009 car development because the rule changes are so big. As such we haven't been developing the FW30 for quite some time.

"Furthermore while I am sure others are well on with 2009 as well - and it is nothing to get excited about - re-learning how to control the principle flow structures around the car is no small task. If you are not on with it early you will be losing in 2009. That is just the aerodynamics too. There is also a need to understand the slick tyres and sort out KERS [Kinetic Energy Recovery System]. There are a couple of reasons then for why we have potentially gone backwards. But it is our job now to correct that next year."

So can Williams re-discover its former glories and win again?

"Absolutely - our target is always to win races and challenge at the top. We will be back there," Michael summed-up.