Nearly 10 million Greek voters head to the ballot box on Sunday for the third time this year to elect a government already bound to apply economic reforms set out in a three-year EU bailout.

The year kicked off for Greece with a general election in January, won by the left-wing Syriza party with 36.34 percent of the vote, followed by the conservative New Democracy bloc at 27.81 percent.

Six months later, Prime Minister Alexis Tsipras called a referendum in which 61.3 percent of Greeks rejected cash-for-reform austerity proposals by the country's creditors.

A third ballot was triggered when Tsipras resigned in August after agreeing to new tax hikes and spending cuts in a fresh EU bailout, the third since 2010, a deal that split his ruling party.

Only Greek citizens aged 18 and above are entitled to vote on Sunday when ballots open at 0400 GMT, provided their rights have not been suspended by a court conviction.

Overall, there are over 9.8 million registered voters, over half of them women, according to interior ministry statistics.

Among them, over 110,000 will be youths voting for the first time.

The minimum requirement for parliamentary representation is 3.0 percent of the vote.

However, the final score of small parties who fall below this threshold directly impacts the percentage of the vote the election winner needs to secure an absolute majority of 151 lawmakers in the 300-seat parliament.

If the parties left out combine for 5.0 percent of the vote, the winner will need 38.5 percent for an absolute majority, Ethnos daily noted on Saturday.

If they combine for 15 percent of the vote, the winner needs only 34.4 percent for an absolute majority.

In most opinion polls, however, both Syriza and New Democracy are below those thresholds.

Analysts say the campaign could have similarities to the 2000 election, when the conservatives celebrated victory early in the evening before tallies showed the vote was actually won by the socialists by a mere 72,000 votes.

They add that a high abstention rate will primarily hurt Syriza, as most undecided voters picked the left-wing party in January.

Voting is nominally compulsory in Greece. The largest age group among Greek voters is made up of people over 71 years old -- over 2.2 million -- who are legally exempt from the obligation.

Exit polls will be released when ballots close at 1600 GMT, and first official estimates will be delivered by the interior ministry after 1800 GMT.