Reflecting differences over the deal pushed through by the pro-Western government of Prime Minister Zoran Zaev, the winner of Sunday's ballot is not expected to secure an outright majority, meaning a run-off vote would be held on May 5.
Alexis Tsipras called the confidence motion after his right-wing coalition partner Panos Kammenos quit the government on Jan. 13 in protest over the name deal signed between Athens and Skopje last year.
Greece, a NATO and EU member, has long blocked Macedonia's efforts to join the alliance, arguing that use of the term "Macedonia" implies territorial ambitions on its own province of the same name, the birthplace of Alexander the Great.
Macedonia has set September 30 for a referendum on the government's deal in June with neighbouring Greece to change its name to the Republic of North Macedonia which would largely clear the path for it to join NATO and the European Union.
The former Yugoslav republic must change its constitution to formalize the deal. Opposition parties and large sections of the population in both Greece and Macedonia are against the agreement, arguing it offers too many concessions to the other country.
Following the break-up of Yugoslavia in 1991, Greece's northern neighbour took the name Macedonia. Athens refused to accept it, saying it implied territorial claims over the Greek province of Macedonia and an appropriation of ancient Greek culture and civilisation.
Macedonia and Greece have been holding talks to resolve the long-running row over the use by the former Yugoslav Republic of the name Macedonia, which Greece says implies a territorial claim because its northern province has the same name.