Paris - Motorsport's governing body FIA convened in Paris on Tuesday to decide whether the aerodynamic designs of the cars of Formula One leaders Brawn GP and two other teams are legal.

Brawn GP, Toyota and Williams use a type of diffuser which rival teams claim does not conform to new regulations introduced this season.

Their protests were originally turned down, but the FIA's Court of Appeal is reviewing the case in Paris and is expected to announce a ruling on Wednesday.

The diffuser is an aerodynamic feature which channels air out of the back of the chassis. It affects a Formula One car's downforce which in turn enhances speed and performance.

Ferrari, Renault and Red Bull, supported by McLaren-Mercedes and BMW Sauber, protested the legality of the double-diffuser design, but the protests were rejected by race stewards ahead of the season-opening Australian Grand Prix.

Should the court rule the diffusers legal, the seven teams running without the controversial design would have to redevelop their cars at huge cost as soon as possible.

However if the protesters win their case, FIA could scrap the points won in Australia and Malaysia by the three teams concerned, or allow the results to stand and order changes from Sunday's Chinese Grand Prix onwards.

Brawn GP driver Jenson Button of Britain goes into the race as championship leader on 15 points after winning the first two races. The Brawn team lead the constructors' championship with 25 points, ahead of Toyota on 16.5 points.

Brawn GP team boss Ross Brawn said he was optimistic the Court of Appeal would agree with the race stewards and sanction its diffuser design.

"I would just be surprised if the appeal court can make judgements on technicalities - it's quite a complex technical matter," he told BBC Sport.

"You can't be 100 per cent confident but I hope common sense prevails on their side."

Renault's double world champion Fernando Alonso meanwhile warned that if the diffuser design is ruled legal the championship "could be more or less decided."

"If the diffusers are legal, then the Brawns are going to be nearly unreachable for any other team," he said.

Meawnhile Ferrari, who have not won a single point so far, have decided team manager Luca Baldisserri will not travel to the Chinese Grand Prix but stay behind to work on car development.

"The goal is to anticipate as much as possible the introduction of new technologies to reduce the performance gap as fast as possible," Ferrari said on its website.

Australian engineer Chris Dyer will take over Baldisserri's track-side duties in Shanghai.