Greek Prime Minister Alexis Tsipras said he was willing to accept unpalatable compromises to secure a deal with international creditors provided he gets debt relief in return, something that Germany refuses to countenance.
With Greece heading towards possible default and bankruptcy, he told his negotiating team before it took a counter-proposal to Brussels that without debt relief he would reject any settlement that isolates his country from the rest of Europe.
In little more than a fortnight, Athens must repay 1.6 billion euros ($1.8 billion) to the International Monetary Fund with money it does not have.
Greek ministers arrived in Brussels on Saturday to resume negotiations on a cash-for-reforms deal with the EU and IMF creditors that ended in stalemate on Thursday.
The counter-proposal offering concessions on budget issues is designed to break the deadlock that is threatening Greece's future in the euro zone.
Tsipras, who was elected in January on promises to end austerity, made it clear he was willing to give ground but with strings attached that German Chancellor Angela Merkel is unlikely to accept.
Tsipras used the term "sustainable solution" to refer to a long-standing demand for large parts of Greece's mountainous debts to be written off or rescheduled - something he believes is vital if the Greek economy is to start getting back on its feet after a six-year depression.
Much of that debt is owed to Germany, the biggest contributor to Greece's 240 billion euro bailouts. Any acceptance by Merkel that the money might never be paid back would almost certainly create uproar among the country's politicians and taxpayers.
EU officials question Greek assertions that the debt is asphyxiating the economy. The government's immediate problems are with repaying loans from the IMF and European Central Bank while privately held debt is relatively modest following a major write-down in 2012.
On Friday, EU officials said representatives of euro zone member states had formally discussed a series of scenarios, including for the first time one which involved a possible Greek default on the repayment to the IMF due by the end of June.
Athens, which attended a meeting of the official-level Euro Working Group on Thursday, has denied that any such scenario had come up.
Defaulting on a repayment to the IMF, the global lender of last resort, would have profound consequences. The ECB would probably have to halt emergency lending that supports Greek banks, which have suffered huge withdrawals by anxious savers.
Athens would then probably have to impose capital controls on deposit withdrawals and payments abroad in a series of events that would put Greece's future in the euro in grave danger.