Greek lawmakers are to debate the confidence vote in the new Greek government for three days with a vote expected on Tuesday night.
Papandreou announced a major government reshuffle on Friday aimed at securing the green light to push ahead with further austerity measures amid public protests.
He axed finance minister George Papaconstantinou, who had been criticised for failing to jumpstart the economy after 18 months. He was replaced by Evangelos Venizelos from the defence portfolio.
The Greek government is trapped between pressure from the European Union and the International Monetary Fund to introduce tougher austerity measures in return for a financial bailout.
A controversial 28,4 billion euro budget plan of fiscal belt-tightening must be adopted by the end of the month in order to convince creditor nations to continue with financial aid to the country.
Eurozone finance ministers are to begin talks on Sunday in Luxemburg aimed at unblocking the next tranche of loans to allow Greece to service its debts through the summer.
They will also mull a second long-term bailout package, expected to almost match the 110 billion euro EU-IMF deal agreed last year.