With just 11 days until the country heads to the polls, seven leaders including former leftist prime minister Alexis Tsipras and conservative challenger Vangelis Meimarakis will cross swords in a debate which will be shown at 1800 GMT on state broadcaster ERT.
Tsipras is hoping to pull forward from a neck-and-neck race between his radical leftwing Syriza party and Meimarakis' New Democracy party.
In addition to a challenge from the right, the 41-year-old will also be under pressure from Popular Unity, a breakaway party made up of former Syriza cadres who rebelled when Tsipras's government signed an unpopular third EU bailout in July.
For the first time, they will then be able to briefly ask each other questions in the final segment of the session -- around midnight.
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Though limited in scope, the question-and-answer format is seen as a badly-needed upgrade to a procedure characterised for years by boring monologues.
"We have practically never seen journalists really corner political leaders and expose weak points and contradictions in their claims," writer Christoforos Kasdaglis told Efimerida ton Syntakton daily.
In addition to Greece's ongoing economic crisis and the bailout, migration is turning into a key campaign issue with the Greek islands struggling with a huge influx of refugees from war-torn Syria, in addition to economic migrants from Afhanistan, Pakistan and other poor nations.