Max Mosley, the FIA president, last week expressed the view that there will probably be what he describes as a 'showdown protest' over the design of the aerodynamic rear diffusers fitted to several cars.

It seems that the designs of the ramp-like aerodynamic appendages on the Brawn, Toyota and Williams have been questioned by rivals, who think that the wings are bigger than the regulations originally intended.

Up to now the FIA has said that it believes the designs are within the wording of the regulations, but the matter has become more complicated with at least one team believed to have written to the governing body to state its belief that the design is illegal. Mosley feels that a formal protest over the Australian Grand Prix weekend may be the only way to resolve the matter.

In an interview with The Daily Telegraph on Saturday, Mosley said: “It's a very clever device and you can make a very good case for saying that it's legal and a very good case for saying that it's illegal. It's going to be difficult.

“What's actually happened is that teams are saying ‘We think it's illegal for this and this reason.’