Updated numbers on that first key exit poll:
WATCH: Tymoshenko Says Exit Polls Manipulated
First preliminary results from the Central Election Committee, with less than 1 percent of the votes counted: Poroshenko had 919 votes, followed by Zelenskyy with 717, and Tymoshenko with 447.
WATCH: Poroshenko Says Russia Did Not Want Him In Second Round
Poroshenko said he felt "no euphoria" following the exit poll results.
"This is a harsh lesson for me and the authorities as a whole. It is a reason to work on our mistakes," he said at his campaign headquarters in Kyiv.
Video of Zelenskyy greeting the first exit poll, which placed him first with around 30 percent support.