If five teams do not sign and return letters that are being sent to them individually by the FIA, they will be deleted from the 2010 entry list and therefore locked off the grid for 2010.

It is suggested that the barred teams could later buy one of the smaller new entries and therefore ultimately race next year, but the latest rumour is that the teams' alliance FOTA is likely nearing its last days.

A breakaway world championship is being dismissed by astute observers as nothing more than a threat, meaning that only those who do not intend to race in a premier open-wheel category in 2010 will let the Friday deadline pass without signing up.

Only McLaren, BMW, Renault, Toyota and Brawn are listed as provisional on the initial FIA entry list, as Ferrari and Red Bull's two teams are bound to compete according to (albeit disputed) existing agreements.

Of the aforementioned five, it is rumoured that McLaren, Brawn and BMW are more eager to split with FOTA and sign up for 2010 rather than risk being left off the grid in the event that a breakaway is not established.

For FOTA members to split, it will require the unanimous agreement of the Geneva-based alliance, following the recent penning of a $50m bond forbidding unauthorised defection.

For Ferrari and the Red Bull teams to pull out of F1, they risk breaching not only disputed agreements with the FIA, but separate ones with Formula One Management, potentially sparking costly legal action.

If McLaren, Brawn and BMW join Williams, Force India, Ferrari and the Red Bull teams on the unconditional 2010 entry list, Renault and Toyota would be isolated outside F1 and with only four cars to field in a rival series.

Therefore, if they are not willing to accept the FIA rules, they would simply walk away from formula one, or turn to existing alternate competitions such as Le Mans.

In conversation with Switzerland's Blick, Bernie Ecclestone agrees this is a likely outcome.

Asked about Friday's deadline, the F1 chief executive said: "Some of the five teams, which wanted to register but have not yet been accepted, will probably come in. And the others will do what they want to do."

Gerhard Berger agrees that if a resolution is not found, carmakers will walk away. "They will use the splitting of formula one as an invitation to say goodbye," the former driver and team owner told Germany's Auto Motor und Sport.

Niki Lauda believes that the FIA and FOTA continuing the standoff beyond Friday risks destroying the sport. "If they do not agree, then neither of them have futures," he said.

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