The eurozone faces meltdown unless Germany agrees to write off the debts of flailing members, Tony Blair has warned.
The former prime minister said the dilemma was now so severe that a "grand plan" was the only way to avert a dissolvement.
As only Blair could, he also indicated that Britain could still join the single currency area if it solidified.
The statement came as EU leaders prepare for a vital summit this week that could establish the fate of the eurozone.
The problems intensified when it became apparent that newly-elected Greek Prime Minister Antonis Samaras will miss the event after having eye surgery.
Speaking on the Andrew Marr show,Blair said: "The only thing that will save the single currency now is in a sense a sort of grand plan in which Germany is prepared to commit its economy fully to the single currency.
"That means treating the debts of one as the debts of all,which is very hard for Germany to do.
"It means the other countries in the eurozone need to reform, need precise credible programmes of change to reform so that Europe can regain its competitiveness. Otherwise it is quite unfair to ask Germany to pay."
But Mr Blair - a renowned Europhile - refused to believe that the single currency's troubles meant the United Kingdom would never join.
"If they sort it all out and Europe moves forward again then Britain is going to have a very interesting choice to make," he said.