Preparations continue for the scheduled debate between Ukrainian President Petro Poroshenko and his challenger, the comic actor Volodymyr Zelenskiy.
Zelenskiy and Poroshenko are now due to face off in a question-and-answer format at Kyiv's Olimpiyskiy Stadium on April 19, just two days before the runoff vote on April 21.
Opinion polls show Zelenskiy with a comfortable lead over Poroshenko, whom many Ukrainians blame for the slow pace of reform and failure to tackle corruption during his five-year term.
Zelenskiy, who stars on a TV comedy series about a teacher who becomes president after denouncing corruption, won nearly twice as many votes as Poroshenko in the first round, on March 31.
The two candidates had agreed to a debate, but not on details, such as when.
Poroshenko showed up at Olimpiyskiy Stadium on April 14, insisting the debate would take place then.
Zelenskiy did not appear, and Poroshenko ended up holding a rally there with supporters.
Now, both camps say the two candidates will meet at the 70,000-seat stadium on April 19, according to a report by the AFP news agency.
The Zelenskiy team is promoting the event on social media, encouraging the public to be "witness to an event that will go down in the history of Ukraine," according to AFP.
The two men took drug tests earlier this month at Zelenskiy's insistence in a campaign that has been marked by theatrics on both sides.
Poroshenko's campaign team said on April 17 that supporters will be bussed in for free for the event, according to Interfax.
Interior Minister Arsen Avakov said a crowd of "up to 60,000" was expected to attend the debate, adding he would be discussing security matters with representatives of both candidates.
His comments on April 17 come after Ukrainian authorities announced they had captured a Russian military intelligence hit squad responsible for the attempted murder of a Ukrainian military spy ahead of the presidential runoff.
The issue of how to deal with Russia, which annexed Crimea in 2014 and backs separatists in eastern Ukraine, is prominent ahead of the vote, with Poroshenko casting himself as the commander in chief Ukraine needs to defend the country.