Williams is to introduce further tweaks to the rear end of its FW33 in an attempt to challenge for points in the Belgian Grand Prix this weekend.

Prior to the summer break, the former championship-winning team scored on just two occasions, with Rubens Barrichello taking back-to-back ninth place finishes in Monaco and Canada.

Following the summer break, Williams will hope for a stronger second half of the campaign with technical director Sam Michael revealing that the team would take an updated rear wing and diffuser to Spa in an attempt to challenge for points.

"Spa is one of the greatest circuits in the Formula One Championship," he said. "Large variations in terrain provide a challenge to the engineers to cover all of the different corner types, from slow speed curb riding to the flat out Eau Rouge. Race day can be really interesting when the weather changes as it can rain on one side of the circuit and be dry on the other!

"We will bring new rear wings which feature a different drag level and some diffuser modifications to evaluate during practice."

Having scored all of Williams' points thus far in 2011, Barrichello said he was hopeful that the updates would allow him to fight for a third top ten finish of the campaign.

"I love Spa-Francorchamps; the track is very special," he said. "It is the place where I claimed my first Formula One pole position back in 1994. It was in very tricky conditions as the track was drying out, but that is something that happens quite a lot at Spa. We are going to have a new aero package for this race that I hope will give us a better chance to fight for points. It is a real drivers' circuit with no time to breathe during a lap."