The political uncertainty is threatening to set off a chaotic power struggle in Armenia, an impoverished ex-Soviet republic on the borders of Turkey and Iran.
The coalition collapsed a year later, but he stayed on at the head of a left-leaning government cobbled together between the M5S, PD and smaller allies.
Muhyiddin had also avoided a potential political crisis last month, after the opposition backed down from a plan to vote down the budget at the end of the policy stage debate.