Ukrainians are set to vote in the second round of an election that could thrust a comedian with no prior political experience into the presidency of a country at war and wanting transformational change.
Volodymyr Zelenskiy, who plays a fictitious president in a popular TV series, has led opinion polls against the incumbent Petro Poroshenko, whose popularity has been dragged down by patchy efforts to tackle corruption and sliding living standards.
At stake in Sunday's vote is the leadership of a country on the frontline of the West's standoff with Russia following the 2014 Maidan street protests and the annexation of Crimea.
Both candidates have pledged to keep the country on a pro-Western course.
Investors are also seeking reassurances that whoever wins will accelerate reforms that are needed to keep foreign aid flowing and attract much-wanted foreign investment.
Zelenskiy's promise to fight corruption has resonated with Ukrainians who are fed up with politics as usual in a country of 42 million people that remains one of Europe's poorest nearly three decades after winning independence from the Soviet Union.
In the popular TV show Servant of the People, Zelensky plays a school history teacher who gains notoriety when a video of him bad-mouthing the country's leadership goes viral.
He eventually decides to run for president and surprisingly wins.
"I'm just a person, a person who has come to break the system," Zelensky said at a debate last week with Poroshenko in Kiev's Olympic Stadium.
Poroshenko accused him of "making a mockery of the country".
His rise comes at a time of political insurgency in many parts of the world, from Brexit to the election of US President Donald Trump and to the 5-Star Movement in Italy, which was also driven by a comedian.
"I think the top election issue is frustration with the status quo," said Mary O'Hagan, Ukraine Resident Senior Director of the National Democratic Institute (NDI).
Poroshenko was elected amid high hopes for change after the Maidan protests.
O'Hagan says he inherited a difficult situation in 2014 and implemented many reforms but has not convinced voters that he is serious about tackling corruption.
"I think it is fair to say that public opinion has not regarded the current set-up as a sufficient step forward from what there was before, to justify the many sacrifices that people have made following the revolution, in terms of living standards, security, loss of life, displacement," she said.
Zelenskiy's unorthodox campaign relied heavily on quirky social media posts and comedy gigs instead of traditional rallies and leafletting.
Poroshenko has sought to portray Zelenskiy as a buffoonish populist whose incompetence would leave Ukraine vulnerable to Russia.
Ukrainian troops have battled Kremlin-backed separatist fighters since 2014 in a conflict in the eastern Donbass region that has killed 13,000 people despite a notional ceasefire.
"Ukraine needs a leader who can withstand Putin and disrupt his predatory plans for our country," Poroshenko said in a statement released by his office on Thursday.
