Ukraine’s presidential candidates have taken alcohol and drug tests before a run-off vote.

Volodymyr Zelenskiy, a popular comedian who left President Petro Poroshenko far behind in Sunday’s first round, had challenged the incumbent to take the test.

Mr Poroshenko took the test on Friday at Kiev Olimpiyskiy Stadium, the country’s biggest arena where the two rivals are set to have their debate two days before the April 21 run-off.

Mr Zelenskiy took the test at another lab, saying he does not trust the one at the sports arena.

Mr Zelenskiy, who stars in a TV series about a teacher who becomes president after a video of him denouncing corruption goes viral, has made the fight against corruption the focus of his campaign.

He won 30% of Sunday’s vote, while Mr Poroshenko got 16%.

Volodymyr Zelenskiy laughs as he takes a blood test in Kiev, Ukraine. Credit: AP

The strong showing of Mr Zelenskiy reflects the public longing for a fresh leader who has no links to the corruption-ridden Ukrainian political elite.

They hope he can offer a new approach to settling the grinding conflict with Russia-backed separatists in eastern Ukraine.

Ukranians went to the polls on Sunday to choose from 39 candidates in the first presidential elections since 2014.

The people of Ukraine are hoping for a president who can guide the country of more than 42 million out of troubles including endemic corruption, a seemingly intractable war with Russian-backed separatists in the country’s east and a struggling economy.

Election count ballots at a polling station during the presidential election in Kiev, Ukraine. Credit: AP

Zelenskiy proposes a lifetime ban on holding public office for anyone convicted of corruption and calls for a tax amnesty under which someone holding hidden assets would declare them, be taxed at 5% and face no other measures.

However, despite the strong initial numbers of Mr Zelenskiy, it is predicted no candidate will win an outright majority in the first round.

The election will go into a run-off vote on April 21, with the top two candidates.