Jakarta went to the polls in a tight run-off Wednesday with the Christian governor fighting for his job despite standing trial for blasphemy, in a divisive election that has stoked religious tensions in Muslim-majority Indonesia.
Basuki Tjahaja Purnama is facing a Muslim challenger, heavyweight ex-minister Anies Baswedan, in a neck-and-neck race to lead the teeming capital of 10 million people.
The vote is seen as a test of whether the moderate Islam traditionally practised in the world's most populous Muslim country is under threat from the influence of hardliners, who have led mass demonstrations against Purnama.
Purnama, the city's first non-Muslim governor for half a century and its first ethnic Chinese leader, won in the first round in February but not by a big enough margin to avoid a run-off.
The race was already significant as politicians see the job as a stepping stone to the presidency at 2019 polls, but the stakes were raised dramatically by a controversy sparked by claims that Purnama insulted the Koran.
The allegations drew hundreds of thousands of conservative Muslims onto the streets of Jakarta in major protests last year, and led to Purnama -- known by his nickname Ahok -- being put on trial for blasphemy in a case critics see as politically motivated.
After casting his ballot at a polling station in north Jakarta, Purnama made clear the importance of the vote.
"Today's election decides the future of Jakarta," said the governor, who has seen a once-unassailable poll lead shrink amid the blasphemy controversy. "The military and the police are guaranteeing security, so don't be afraid to come out."
Polls opened at 7:00 am (0000 GMT) and will close at 1:00 pm (0600 GMT), with over 7.2 million people registered to vote.
After an anti-Purnama protest last year turned violent, authorities are taking no chances and over 60,000 security forces had been deployed.
Hardline groups had pledged to station monitors at polling booths but police moved to ban the plan, warning it could cause "intimidation".
Early vote tallies from private pollsters due to be released in the afternoon should give an accurate indication of how the candidates have performed although official results will not be announced until early May.
Despite Purnama's first-round victory, former education minister Baswedan, 47, was initially seen as the favourite in the run-off because the votes from a third, Muslim candidate who was knocked out were expected to go to him.
But with tension over the governor's alleged blasphemy subsiding in recent weeks, Purnama has regained momentum. Recent polls show the two candidates almost neck and neck, although most put Baswedan ahead by a wafer-thin margin.
Baswedan, an academic, has been accused of abandoning his moderate Islamic values during the campaign by cosying up to hardliners in a bid to win the support of Muslim voters angered by Purnama's alleged blasphemy.
Purnama's troubles began in September when he lightheartedly said in a speech that his rivals were tricking people into voting against him using a Koranic verse, which some interpret as meaning Muslims should only choose Muslim leaders.
His long-running blasphemy trial began in December, and the verdict is expected within a few weeks.
If he does win the vote and is convicted of blasphemy, he would not automatically be barred from holding office and could avoid jail for a long time by appealing.
Many voters still back Purnama due to his record leading Jakarta since 2014. He has won praise for cleaning up the city's once-filthy rivers and creating more green spaces, although his acerbic style has upset some.
"I voted for Ahok because I'm poor and I have felt the difference -- we're being taken care of," said Tayem, a 62-year-old housewife who like many Indonesians goes by only one name, after casting her ballot.
But some have been swayed by the blasphemy controversy.
"As a Muslim, I will choose according to my faith," Elva Sativia, a 33-year-old housewife, told AFP.