Croatia's incumbent President Zoran Milanovic looks set to win re-election with an overwhelming majority, early exit polls showed.
Results from conducted by Ipsos polling agency and published by state television station HRT, said Mr Milanovic won nearly 78 per cent of the vote from his challenger Dragan Primorac.
Official results were expected later in the evening.
The left-leaning Mr Milanovic comfortably won the first round of voting on December 29, leaving Mr Primorac, a forensic scientist who had unsuccessfully run for president before, and six other candidates far behind.
“I am hoping for a victory,” Mr Milanovic said after voting on Sunday. “I believe in victory because I think I am worth it and because it is important, primarily because it is important.”
The run-off between the top two contenders was necessary because Mr Milanovic fell short of securing 50 per cent of the vote by just 5,000 votes, while Mr Primorac trailed far behind with 19 per cent.
The election comes as the EU and Nato member country of 3.8 million people struggles with inflation, corruption scandals and a labour shortage.
Mr Milanovic, 58, is an outspoken critic of western military support for Ukraine in its war against Russia. He is the most popular politician in Croatia, and is sometimes compared to US president-elect Donald Trump for his combative style of dealing with political opponents.
On Sunday, he again criticised Brussels as “in many ways non-democratic" and being run by unelected officials. The EU position that “if you don’t think the same as I do, then you’re the enemy” amounts to “mental violence", Mr Milanovic said.
“That’s not the modern Europe I want to live and work in,” he said. "I will work on changing it, as much as I can as the president of a small nation.”
Mr Milanovic has also been prime minister, with a mixed record. He has been a fierce critic of current Prime Minister Andrej Plenkovic and the pair have long sparred with each other.
Mr Milanovic regularly accuses Mr Plenkovic and his conservative Croatian Democratic Union party of systemic corruption, while Mr Plenkovic has called him “pro-Russian” and a threat to Croatia’s international standing.
Mr Primorac echoed this position as he cast his ballot. He said the presidential vote was “very important” and "about the future of Croatia … about the future of our homeland, our citizens and really, the direction that it would go from here".
Political analyst Viseslav Raos said the increasingly outspoken Mr Milanovic has no motive to “try to please someone or try to control himself".
“If there was no co-operation with the Prime Minister for the first five years [of his presidency], why would it be now?” he said.
Although the role is largely ceremonial in Croatia, the president holds political authority and acts as the supreme military commander.
Despite limited powers, many believe the presidential position is key for the political balance of power in a country mainly governed by the Croatian Democratic Union (HDZ) since gaining independence from Yugoslavia in 1991.
Mr Primorac, 59, entered politics in the early 2000s, when he was science and education minister in the HDZ-led government. He unsuccessfully ran for the presidency in 2009, and after that mainly focused on his academic career including lecturing at universities in the US, China and in Croatia.
Mr Milanovic denied he is pro-Russian but last year blocked sending five Croatian officers to Nato's mission in Germany, called Security Assistance and Training for Ukraine. He also pledged he would never approve sending Croatian soldiers as part of any Nato mission to Ukraine.
Mr Plenkovic and his government say there was no such proposal.
