Yushchenko has seen his support evaporate in the past five years
Ukraine's President Viktor Yushchenko, the one-time hero of the Orange Revolution, has been eliminated from the country's presidential election.
A run-off will be held on 7 February after no candidate won 50% of the vote.
With more than 90% of votes counted, the president had won only about 5%. Former PM Viktor Yanukovych led current PM Yulia Tymoshenko by some 35% to 25%.
Despite allegations of fraud by candidates, international monitors gave the election a clean bill of health.
Officials from the Organization for Security and Co-operation (OSCE) said the election was of high quality and met Ukraine's democratic commitments.
It was Mr Yanukovych's victory in the 2004 election that was challenged by the Orange Revolution, and later annulled by the Supreme Court.
BBC News, Kiev
Prime Minister Yulia Tymoshenko was instrumental in bringing the current President, Viktor Yushchenko, to power during the Orange Revolution five years ago. But the pair soon fell out, and she is now portraying herself as the heir of the Orange mantle.
Five years ago, Viktor Yanukovych was the villain, tainted by open support from Moscow and allegations of vote-rigging.
Now, both candidates say they favour closer ties with Russia - after five years of increasingly tense relations under President Yushchenko - and the Kremlin seems happy with either.
Mr Yushchenko and Mrs Tymoshenko were allies in the Orange movement, and became president and prime minister in its aftermath.
But they have since become bitter rivals, and the poll highlighted their recent power struggle.
But long before all the ballots were counted, the verdict was clear, says the BBC's Gabriel Gatehouse in Kiev.
Ukrainians had overwhelmingly rejected the man who led the pro-Western protests on Independence Square five years ago.
Disillusionment has grown among voters over the failure to tackle corruption in the intervening years, and to push forward links with the EU, our correspondent says.
As opinion polls had predicted, the first-round winner was Mr Yanukovych, ahead of Mrs Tymoshenko. The two will take part in a run-off in three weeks' time.
On opposing sides of the Orange Revolution in 2004 and 2005, both now favour closer ties with Russia.
Mr Yanukovych has made an extraordinary comeback after his victory of five years ago was ruled fraudulent, our correspondent says.
Yanukovych supporters gathered in Kiev to celebrate on Monday
He seemed delighted to have defeated his old enemy, saying: "Today marks the end of Orange power. There will be no room for (Yushchenko) in the second round. He has officially lost the faith of the people."
Analysts expect Mrs Tymoshenko to pick up more votes in the second round, and the race could be very close.
The leading candidates had accused each other of trying to rig the election, and there have been warnings of unrest after the vote.
But Andrei Magera, deputy head of the Ukrainian Central Election Commission, said there was no evidence of voter intimidation nor organised fraud. "There was nothing similar to mass actions that took place in the year of 2004 when voters with absentee ballots had been carried all over Ukraine by buses," he said.
Mrs Tymoshenko responded to the result by saying: "Despite the great campaign of discrimination that was launched by all the oligarchs who rallied around Yanukovych, people showed their wisdom, trust and faith in me."
She said she was ready for talks with the defeated candidates "so that we can move forward with uniting the democratic forces".
A total of 18 candidates took part in the election.
Turnout was reported to be about 67%.
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