* Centre right seen head-to-head with 5-Star in Sicily vote
* National election must be held by May
Sicilians began voting for a new regional government on Sunday in a crucial ballot seen as a test of national trends ahead of parliamentary elections in the spring.
The contest on the Mediterranean island is expected to be a close race between a resurgent centre right and the anti-establishment 5-Star Movement, with the ruling centre left, weakened by internal divisions, in a distant third place.
Bolstered by the return of four-times prime minister Silvio Berlusconi to the campaign trail, the centre right is looking to reclaim its traditional supremacy over Sicily and show that after years of scandals it is again a force to be reckoned with.
It faces tough opposition from 5-Star, which has never won control of an Italian region and hopes victory in Sicily can propel it to success in the national ballot to be held by May at the latest.
The centre left, which now heads both the Sicilian and national governments, has succumbed to feuding with leftist rivals - a fratricidal struggle that looks likely to wreck its chances of retaining power.
Some 4.5 million Sicilians are eligible to vote for the island's new governor, with opinion polls pointing to a battle between 5-Star's Giancarlo Cancelleri and Nello Musumeci at the head of a centre-right coalition.
Fabrizio Micari, the candidate of the ruling centre-left Democratic Party (PD) may be challenged by Claudio Fava, backed by a cluster of left-wing parties.
A bad showing for Micari would pile more pressure on PD leader and former Prime Minister Matteo Renzi, whose party has splintered after a raft of local vote setbacks in recent years.
5-Star, which leads most national opinion polls with about 27% of the vote, just ahead of the PD, has invested most political capital in the Sicily election, with its new leader Luigi Di Maio campaigning hard on the island since the summer.
The centre-right bloc is made up of Berlusconi's conservative Forza Italia and the anti-immigrant Northern League, each with about 14% of the national vote, flanked by the far-right Brothers of Italy on around 5%.
Exit polls will be issued when voting ends at 10 pm, but the actual vote count will not begin until Monday at 8 am.