Istanbul: Turkish polling stations closed Sunday in a historic runoff election that could extend President Recep Tayyip Erdogan's two decades of rule until 2028.
The NATO member's longest-serving leader defied critics and doubters by emerging with a comfortable lead against his secular challenger Kemal Kilicdaroglu in the first round on May 14.
Kilicdaroglu cobbled together a powerful coalition that grouped Erdogan's disenchanted former allies with secular nationalists and religious conservatives.
Opposition supporters viewed it as a do-or-die chance.
"I invite all my citizens to cast their ballot in order to get rid of this authoritarian regime and bring true freedom and democracy to this country," Kilicdaroglu said after casting his ballot in Turkey's first presidential runoff.
Erdogan's almost five-point first-round lead came in the face of one of the world's worst cost-of-living crises - and with almost every opinion poll predicting his defeat.
The 69-year-old looked tired but at ease as he voted with his wife Emine in a conservative district of Istanbul.
"I ask my citizens to turn out and vote without complacency," Erdogan said.
Emir Bilgin heeded the Turkish leader's call.
"I'm going to vote for Erdogan. There's no one else like him," the 24-year-old said from a working-class Istanbul neighbourhood where the young future president grew up playing street football.
Kilicdaroglu re-emerged a transformed man after the first round.
The former civil servant's message of social unity and freedoms gave way to desk-thumping speeches about the need to immediately expel migrants and fight terrorism.
His right-wing turn was targeted at nationalists who emerged as the big winners of the parallel parliamentary elections.
The 74-year-old had always adhered to the firm nationalist principles of Mustafa Kemal Ataturk - a revered military commander who formed Turkey and Kilicdaroglu's secular CHP party.
But these had played a secondary role to his promotion of socially liberal values practised by younger voters and big-city residents.
Analysts question whether Kilicdaroglu's gamble will work.
His informal alliance with a pro-Kurdish party that Erdogan portrays as the political wing of banned militants left him exposed to charges of working with "terrorists".
And Kilicdaroglu's courtship of Turkey's hard right was hampered by the endorsement Erdogan received from an ultra-nationalist who finished third two weeks ago.
Some opposition supporters sounded defeated after emerging from the polls.
"Today is not like the last time. I was more excited then," Bayram Ali Yuce said in one of Istanbul's heavily anti-Erdogan neighbourhoods.
"The outcome seems more obvious now. But I still voted."