Greeks fed up with austerity voted Sunday in elections that could decide their future in the eurozone amid unprecedented external pressure not to vote for a radical leftist party.
Some 9.8 million Greeks began voting at 0400 GMT in a showdown between the conservative New Democracy party and the anti-austerity Syriza party that has spooked European leaders and the markets.
"I hope that the vote will lead us to the formation of a stable government that will immediately address the problems troubling the Greek people," President Carolos Papoulias said after casting his vote.
The ballot opened smoothly but around 1000 GMT a prominent television station, Skai TV, was evacuated after an apparent bomb threat.
"Somebody threw a grenade outside the station and the building has been evacuated until the police bomb squad can examine it," a staff member told AFP.
It was not immediately clear if the grenade, which failed to explode, was live, a police source said.
The man at the centre of the storm, Syriza leader Alexis Tsipras, said his side would win and Greece would keep its place as an "equal" member in a "changing" Europe.
"We have conquered fear," Tsipras said after casting his vote in the working class Athens district of Kypseli, an apparent reference to criticism that his threat to scrap a multi-billion EU-IMF loan agreement endangers Greece's eurozone membership.
Former Greek PM George Papandreou told the BBC Sunday that the vote was a "make or break" moment for Europe as a whole.
Greek newspapers said the vote was the most critical since the end of military rule in 1974, as conservative chief Antonis Samaras argued that a "new era" would begin for the recession-hit eurozone state on Monday.
"Today the Greek people speak. Tomorrow a new era starts for Greece," Samaras said in his hometown of Pylos in the southern Peloponnese peninsula.
"We must have a strong united front and international credibility to achieve the best for Greeks, inside the eurozone, whilst keeping all that is positive in the loan agreement, all that is positive about the country's European character," said Socialist leader Evangelos Venizelos.
Venizelos is seen as the most likely partner for the Conservatives in a coalition government.
German Chancellor Angela Merkel on Saturday said it was "extremely important" for Greeks to elect lawmakers who would respect the terms of the bailout, which Tsipras insists will be "history" on Monday.
Eurogroup chief Jean-Claude Juncker also warned on the eve of the momentous vote -- the second in six weeks after May 6 elections failed to produce a government -- that choosing Syriza could have "unpredictable" consequences for the eurozone as global markets watched with bated breath.
Many Greeks would grudgingly admit Juncker has a point.
"We signed something (the bailout deal). We can't just take it back," said 68-year-old Emmanuel Kamkoutis after casting his vote, which he said went to a centre-right party.
Voting ends at 1600 GMT, with first results expected by 1900 GMT.
"Around 1800-1830 GMT we will have a safe sample from 5,000 polling stations," Marika Lambrou, executive director of Singular Logic, the official data keepers of the election, told NET.
Germany's Bild newspaper added to tensions ahead of the vote with an open letter telling Greeks their ATMs had euros only because "we put them there."
"If the parties who want to be through with austerity and reforms win the election and contravene every agreement, we will stop paying," it said.
Tsipras argues that the mood in Europe is shifting against austerity and that the European Union and International Monetary Fund will not want to risk a Greek eurozone exit that would send shockwaves through the global economy.
Samaras wants a more moderate renegotiation of the bailout deal and warns that a vote for Tsipras could bring back the old drachma currency.
Polls show an overwhelming majority of Greeks want to keep the euro.
In their public comments at least, European leaders warn that Greece must respect its international debt commitments or risk leaving the euro club, and the EU and the IMF have suspended loan payments until after the elections.
Greece has been forced to seek bailouts twice, first for 110 billion euros in 2010 and then for 130 billion euros this year plus a 107 billion euro private debt write-off -- for a total of 347 billion euros ($439 billion).
There may be some room for compromise on the bailout conditions, such as extending a crucial deficit-cutting deadline to 2016 from 2014.
But for many Greeks a fine-tuning of the terms may not be enough as public anger is rising against the steep pay and pension cuts seen since the crisis first exploded in 2009, setting off a chain reaction across Europe.
Greece is now in its fifth year of recession, prompting many young Greeks to vote with their feet by emigrating, while local media warn the state will run out of cash to pay public-sector salaries and pensions on July 20.
No single party is expected to secure a majority in parliament, and the days ahead are likely to be dominated by coalition talks.
Analysts say New Democracy would find it easier to form a coalition if it wins -- although it might struggle to secure a strong majority in parliament.
It may be trickier for Syriza to set up a leftist coalition.
"Both scenarios are not very easy," said Vassiliki Georgiadou, a political science lecturer at Panteion University in Athens.