Chinese Grand Prix - preview

With two peerless wins and an FIA ruling on his side, Jenson Button has arrived in Shanghai with his sights set firmly on a hat-trick.

Last year's Chinese Grand Prix was held just six months ago, and since then the running order has been turned on its head: In 2008, Lewis Hamilton stormed to a decisive victory while Jenson Button finished 16^th, and lapped by Hamilton.

Now, in 2009, Button is the title favourite and all Lewis has to show for his season so far is a disqualification, a soggy seventh place in Malaysia and an upcoming court date which could, worst case scenario, see McLaren thrown out of the championship.

This weekend, McLaren are said to be introducing new aerodynamic parts which should help close the gap, but they've been so far behind up to now that their hopes are a modest points finish.

The ruling on Wednesday that the double-decked diffuser used by Button's Brawn, and the also Williams and Toyota cars, is legal sets straight a point of controversy that has been debated for over a month now. The innovative interpretation of the technical rules by these three teams has been found valid by the FIA's independent Court of Appeal, and now you can expect the other teams to be working night and day to finalize their own copies. McLaren and Renault are set to unveil their versions here this weekend, while Ferrari are estimating theirs will debut in Spain, four weeks from now - time which could further erode their hopes of holding onto their constructor's title.

The cars which are closest to the performance of the Brawns are Toyota, Williams and Red Bull Racing, and the latter two are due a strong result. They have yet to convert their 2009 machines' enormous potential into representative results. So far we've seen their performance squandered through accidents or poor strategic decisions during the race.

One element that will definitely mix things up at the Shanghai International Circuit is KERS, as the track features some extremely long straights.

If Ferrari, Renault, McLaren or Nick Heidfeld's BMW-Sauber can qualify reasonably well, expect them to make up places at the start and then be very hard to pass. This could make an impact on the non-KERS cars strategies, choosing a shorter first stint.

Therefore Jenosn and team mate Rubens Barrichello will be hoping for a few of their non-KERS allies to create a buffer on the grid between them and those with a boost button.

A couple of weeks ago Kimi Raikkonen spoke of how the diffuser ruling would affect the outcome of this year's championship. There are still 15 races to go and everything to play for, but Ferrari and McLaren need to do more than copy Brawn, they need to innovate and make fewer mistakes if they're to deny Jenson his surprise title.