ReutersProtesters take part in an anti-austerity pro-government demonstration in front of the parliament in Athens February 11, 2015.After two steps back and one forward last week, it is crunchtime in the talks over Greece’s finances—and its future in Europe’s currency union. Talks start in earnest at a meeting of eurozone finance ministers in Brussels on Monday night. Any changes to the content or expiration date of Greece’s existing €240 billion ($273 billion) bailout have to be decided by Friday, to give national parliaments in Germany, Finland and the Netherlands enough time to approve them before the end of the month. Without such a deal, Greece will be on its own on March 1, cut loose from the rescue loans from the eurozone and the International Monetary Fund that have sustained it for almost five years. There have been some positive signs in recent days. After a meeting Wednesday, in which eurozone finance ministers couldn’t even settle on a joint statement on how to proceed with negotiations, Prime Minister Alexis Tsipras agreed Thursday to begin talks with international institutions on what measures his government would be willing to take in return for continued aid. On Friday, officials in Brussels and other European capitals floated a new proposal that could combine demands from Greece’s creditors to extend the old rescue program with a refusal from Athens to do just that. Under that plan, the final €7.2 billion installment of Greece’s old bailout could be sliced into smaller tranches to be disbursed over the coming months in return for different overhauls and budget cuts. “Legally speaking, [such a deal] would have to be an extension” of the old bailout program, one European official said. But, given the changes to the conditions attached to new aid, “if you’re a Greek politician, you can call it a new program or a new agreement.” A German official suggested that adhering to 70%, or even 50%, of the old measures could suffice, given the right mix and broad compliance with the fiscal and economic goals of the old bailout. An expanded version of this report appears on WSJ.com.