While Formula One has focussed on 'Liegate' for the last week or so, today, the latest McLaren saga is put on the back boiler as the FIA rules on another issue that has overshadowed the start of the 2009 season.

Today, in Paris, the FIA's International Court of Appeal will hear evidence from various parties that could well decide the outcome of the 2009 Formula One World Championship, after just two races.

Having been declared legal in Melbourne, Ferrari, Renault and Red Bull subsequently appealed the Stewards' decision regarding the diffusers on the Williams, Toyota and Brawn.

In the opening two races, the three teams using the diffusers in question have been highly competitive, with Brawn winning both events and Toyota currently second in the Championship. Ferrari, on the other hand, has yet to score a point, while McLaren clearly has its own problems.

Two-time world Champion Fernando Alonso is under no illusion, if the International Court of Appeal agrees with the Melbourne stewards the 2009 title fight is already a lost cause.

"It's a complicated issue, but the championship could be more or less decided," said the Spaniard. "If the diffusers are legal, the Brawns are going to be nearly unreachable for any other team."

Fearing that the Melbourne decision will be upheld, it is known that several teams are already working on their own version of the 'questionable' diffusers, however, Alonso is quick to stress that such a move will not make the teams instantly competitive.

"You have to work on the whole car," said Renault driver, according to the Guardian. "It's not just about adding the diffuser and suddenly the car is a second quicker. The diffuser makes you go fast if you have a new front end, new sidepods, a new engine cover. You have to rebuild the whole car, and that would take a lot of months."

And with the teams having agreed to an in-season testing ban, Brawn, Toyota and Williams could enjoy their obvious advantage for a lot longer.

All the teams bar Toro Rosso and Force India will attend today's hearing, the result of which will be made public tomorrow.