According to the Austrian team, the RB6 was simply unsuited to the long straights of Spa and Monza, and will return to dominance on the more conventional circuits that are set to host the last five races of 2010.

But another line of thinking is that the tougher flexible wing and floor tests, introduced by the FIA amid suggestions the Adrian Newey-penned car is illegally bending at high speed, have hurt the pace of Mark Webber and Sebastian Vettel.

The Sportwoche publication said the team had to make last-minute changes before Friday practice at Monza, which explains the bright green aerodynamic paint seen initially at the rear of the car in Italy.

"It has been a smear campaign against us," said Red Bull's motor racing consultant Helmut Marko, "and now we have the result."

But other elements at the team insist the new tests have had no impact.

"Red Bull say it's not making any difference but I'm hopeful," said McLaren's Jenson Button.

BBC commentator Martin Brundle commented: "Red Bull absolutely insist that they will be back to their dominant pace in Singapore.  We will see."