Comedian Volodymyr Zelenskiy and Ukrainian leader Petro Poroshenko Wednesday finally agreed to a debate to close a presidential campaign that has at times descended into farce. The press teams of both candidates however confirmed the pair would meet tomorrow afternoon at the sports arena that seats 70,000 people, ahead of Sunday's decisive second-round vote.

Poroshenko originally called the event for last Sunday but Zelenskiy was a no-show, leading the incumbent to hold a one-man debate next to an empty podium at a Kiev stadium.

With Zelenskiy scoring 72 percent support to Poroshenko's 25, according to the most recent opinion poll, this could be the last chance the incumbent has to boost his flagging campaign.

Until he announced his candidacy at the start of this year, 41-year-old Zelenskiy's political experience was limited to playing Ukraine's president in a popular TV show. His team was promoting the debate on social media, encouraging the public to be "witness to an event that will go down in the history of Ukraine." They said it would be the "largest scale" event of its kind ever staged in the country.

The two men took drug tests earlier this month, after Zelenskiy insisted this was a requirement before any debate. Critics say the electorate knows next to nothing about what the untested Zelenskiy would do in power. But supporters say only a fresh face can clear up Ukraine's endemic corruption, kick start a stalling economy and hope to address an ongoing conflict with Russia-backed separatists in the east.