Formula One's season of the unexpected will likely continue its unpredictable pattern at the Chinese Grand Prix, but at least championship leader Jenson Button now knows his Brawn GP car is legal.

The Briton, victor in both the season-opening Australian and rain-affected Malaysian races, received the news he wanted to hear Wednesday when the sport's governing body ruled the diffuser fitted to his car did not breach regulations.

The decision by the International Motoring Federation (FIA) International Court of Appeal means Brawn, Williams and Toyota are free to continue racing in the competitive cars that have served them so well this season.

It also avoided the potentially disastrous situation of all three teams being stripped of their points and starting all over again.

"Based on the arguments heard and evidence before it, the court has concluded that the stewards were correct to find that the cars in question comply with the applicable regulations," the FIA said.

Hamilton on the back foot

In contrast, defending champion Lewis Hamilton, who has been embarrassed by his part in the lying scandal that erupted after the Australian Grand Prix, remains on tenterhooks as he awaits a ruling on his and McLaren's future.

They are expected to appear at a meeting of the FIA?s World Motor Sport Council in Paris on 29 April where McLaren?s deliberate misleading of the stewards at the Australian race will be analysed in detail.

The case, which has already cost Hamilton his points gained in Melbourne and much of his once-glowing reputation, has also cost long-serving McLaren team manager Dave Ryan his job.

Since taking the drivers' title at the last corner of last season's final race in Brazil, Hamilton has struggled to show the form of earlier times and complained that his car lacks the performance to make him competitive.

This in turn has added a note of desperation to the McLaren 'winning mentality' approach. It may have been replaced by a 'win-at-all-costs' approach.

McLaren, however, did not join Ferrari and others in the case against Brawn, Williams and Toyota, claiming they did not have the energy to spare for anything other than improving their own car.

World's fastest-moving soap opera

All of which, together with the politics, chicanery and melodrama that have turned modern Formula One into the world's fastest-moving soap opera, suggest that another race weekend could be overshadowed by off-circuit stories.

The romance of Button's triumphs for the new Brawn team, an outfit that rose from the ashes of the defunct Honda team, have made made history, but the Briton has urged some caution.

"I am understandably delighted with how our season has begun but we are only two races in and everyone at the team is aware that our competitors will not stand still," he said.

"We fully expect a tough fight from here if we want to continue our early successes."

Toyota should be their strongest rivals again with Italian Jarno Trulli extending his bright start to the year after finishing third and fourth.

Williams German driver Nico Rosberg could also be a threat.

The two big powers of the sport, Ferrari and McLaren, have only one point between them this season, won by Hamilton in Malaysia, and need a massive improvement to force their way back into the title race.

Ferrari have reshuffled their pit-crew in a bid to add an edge to their performances and know how they fare in China could shape their season.

"The Chinese GP must be a turning point for the Scuderia after a bad start to the season," the team said after crisis talks following their failure in Malaysia.