IT'S A victory for Brawn GP, Toyota and Williams off the track.

The International Court of Appeal of Formula One's ruling body, FIA, has ruled that the controversially-designed diffusers of Brawn GP, Toyota and Williams are legal, after a day of appeal hearings and deliberations.

A panel heard eight hours of strongly worded evidence on Tuesday after complaints that Brawn, Toyota and Williams, are using an illegal diffuser.

And the five International Court of Appeal judges said the designs 'comply with the applicable regulations'.

All three teams are free to race in the Chinese Grand Prix in Shanghai this weekend.

This ruling has major implications on the title race and keeps Brawn and Jenson Button's leads in the team and drivers' championships respectively.

The verdict means there will now be a major scramble from the rest of the pack to follow similarly-designed diffusers.

The FIA statement said full reasons for this decision will be provided in 'due course'.

But has this small little rear diffuser been the sole difference between the form of the accused trio and the rest of the field, especially the big teams that have been humbled by them, namely McLaren, Ferrari, BMW Sauber and Renault?

In the team standings, Brawn lead, followed by Toyota and BMW Sauber. Renault come next, then Williams.

In the drivers' standings, the Brawn pair of Jenson Button and Rubens Barrichello lead from Toyota's Jarno Trulli and Timo Glock.

But BMW Sauber's Nick Heidfeld and Renault's Fernando Alonso come next before you finally get Williams' Nico Rosberg.

Does that suggest clear-cut advantage?

It doesn't explain how Red Bull are also very close to the 'diffuser trio' in terms of qualifying speed and race speed, only for bad luck, mistakes and unfortunate circumstances to have robbed them of deserved points.

Ferrari, Red Bull and Renault lodged their appeal in Australia after stewards rejected their protests over the diffusers. BMW Sauber lodged a similar protest and appeal in Malaysia.

But the big teams have to do more than gripe about their failed appeal.

Let's look at Ferrari first, the worst of the lot.

Zero points from the first two races is their worst start to a world championship campaign since 1992.

Kimi Raikkonen had Kers problems in practice in Malaysia, while team-mate Felipe Massa spectacularly failed to progress beyond qualifying's first session.

This, after the team mistakenly assumed his time would be quick enough to progress into the second qualifying phase.

Sidelined

On race day, Raikkonen went plummeting down the order after a premature switch to wet tyres and was subsequently sidelined with more Kers issues.

Massa repeatedly found himself with the wrong tyres at the wrong time and eventually finished ninth.

McLaren?

Well, if they can stop concentrating on misleading stewards, and avoid being unnecessarily charged with the possibility of being banned from this year's championship (like the prospect they face on 29 Apr), they could actually come quite close to securing a good number of points through Lewis Hamilton's real skills (in driving) when others blunder on track.

Renault?

Let's say if the Kers acceleration boost feature hadn't been introduced this season, Alonso would really be struggling.

Only his canny instincts have kept him poking his nose up front, but it's clear he held up everyone in Malaysia once Barrichello overtook him on the fourth lap and pulled out an amazing six seconds a lap later.

So the big boys really need new diffusers, reliable Kers, better grip and downforce, more speed, and possibly the equivalent of an overnight miracle if they are to be in real contention this season.

Let's see then, how they fare against Brawn, Toyota and Williams starting this weekend at the China Grand Prix.