Two of the more outspoken critics of Red Bull Racing's so-called 'flexi-wing' have expressed surprise and satisfaction after new tests were imposed on all teams at the Belgian Grand Prix.

Concern that the front wings on both Red Bull's RB6 and Ferrari's F10 were deflecting enough under aerodynamic loads on track to create a performance advantage first arose at the British Grand Prix, and have subsequently led to the FIA introducing greater stress tests at Spa-Francorchamps. Although both teams claim that they passed the revised inspection without problem, both McLaren's Martin Whitmarsh and Mercedes' Ross Brawn believe that there is a noticeable difference in the wings this weekend.

"I wasn't that confident that [the problem] would be nailed, but I have to say... the wings were of a different stiffness and positional domain than they had been in previous races," Whitmarsh told Reuters reporters on Saturday evening, "I think we could all see it, and the evidence that was collected yesterday showed that, in regards to stiffness and position, the front wing endplates of those cars appear to be in a different domain."

Although Red Bull still secured its twelfth pole position in 13 races, courtesy of Mark Webber, Brawn agreed that there had been a difference in the attitude of the wings.

"I think all of us can see that what was visible in the last couple of races doesn't seem to be the case here," the former Ferrari man confirmed, "I don't know what has happened, but it looks visually to me, to be different."

Further tests designed to avert the spread of flexible parts, with attention turning to the floor of the cars, are expected to be introduced at the Italian Grand Prix in two weeks' time.