International monitors have given the presidential election in Ukraine a clean bill of health.
The European Security Organisation says the first round on Sunday was of high quality and met the country's democratic commitments.
A second round will be held on 7 February after the vote failed to produce a clear winner. No candidate won 50% of the vote.
The leader of the 2004 Orange revolution Viktor Yushchenko has been eliminated.
With more than 90% of votes counted, he had won only about 5%.
Former Prime Minister Viktor Yanukovych led current PM Yulia Tymoshenko by some 35% to 25%.
Mr Yanukovych's victory in the 2004 election was challenged by the Orange Revolution, and later annulled by the Supreme Court.
Mr Yushchenko and Mrs Tymoshenko were allies in the Orange movement, and became president and prime minister in its aftermath.
But the BBC reports they later became bitter rivals and the poll highlighted their power struggle.
Both Mr Yanukovych and Mrs Tymoshenko now favour closer ties with Russia.