The EU on Monday congratulated Alexis Tsipras on his left-wing party's election victory and said Greece has "no time to lose" in implementing the reforms under its international bailout.
Tsipras secured his second mandate as prime minister this year at a snap general election Sunday that should allow him to drive through the unpopular reforms under a third bailout worth up to 86 billion euros.
"The commission congratulates Alexis Tsipras for his victory," European Commission spokesman Margaritis Schinas told reporters.
He recalled that under Tsipras's previous leadership, Greece already "committed to ambitious programme of reforms" to revive the country's economy as he led the negotiations that culminated in the bailout deal signed in Brussels in August.
"The new government will now have the mandate to carry out those reforms… There is a lot of work ahead and no time to loose."
Schinas said Greece's creditors – the EU, the European Central Bank and the International Monetary Fund – were expected to meet over the next few months to conduct a review aimed at releasing new funds under the bailout deal.
With around 90 percent of votes counted, the SYRIZA party looked set to secure close to an absolute majority in the country's 300-seat parliament, with a smaller nationalist party expected to join forces and push it over the top.
The commission also welcomed what it saw as the "ample representation of pro-European parties" in parliament that are committed to a strong Greece within the 19-country Eurozone, Schinas said.
He added that Commission President Jean-Claude Juncker has already written to Tsipras and will talk to him later in the day.
Tsipras was expected to see Juncker in Brussels Wednesday for an EU summit on the refugee crisis, which is hitting Greece particularly hard.