The Prime Minister of Greece is due to hold crunch talks with eurozone head Jean-Claude Juncker.
Antonis Samaras is expected to ask for more time to implement the tough spending cuts demanded by the European Union and International Monetary Fund.
Mr Samaras, who told the German newspaper Bild that Greece required "breathing space" to fulfill its commitments, will also meet French President Francois Hollande and German Chancellor Angela Merkel later this week.
Greece is due to receive the next instalment of its next 31.5 billion euro (£24.7 billion) bailout payment next month.
Without the cash, Greece faces the prospect of defaulting on its vast public debt and subsequent exit from the euro.