After a remarkably peaceful election given the bloody standards of Cambodian politics, long-suppressed tensions may soon erupt.
The country's political culture has long embraced exclusion, defined power as absolute and demands, at best, cautious optimism. Democracy cannot yet be said to have been successfully transplanted.
First, should he lose, co-premier Hun Seen may have to be prised from the power he has wielded for 18 years. But even in the event of victory, the country's political instability may continue.
For more than 10 months there have been persistent rumours of a split within Mr Hun Sen's ruling Cambodian People's Party (CPP).
The division has been driven in large part by disagreement over his tactics in ousting former premier Prince Norodom Ranariddh and a feeling that Mr Hun Sen has hijacked the party.
That domination and a strong showing by the CPP could prompt Mr Hun Sen to marginalise party moderates, while a poor performance could force a purge of the CPP.
Foreign diplomats fear open confrontation, and party sources and Western military observers agree the CPP-dominated, 130,000-strong military and so called 'fighting police' have already taken sides.
