It has been an ugly presidential election campaign in Ukraine.
By Helen Fawkes
BBC News, Kiev
Mr Putin is backing Mr Yanukovych's candidacy
Voters have witnessed dirty tricks, some of them inspired by Soviet times.
There have been allegations of assassination attempts, media bias and intimidation.
Finally Ukrainians get to choose their new leader on Sunday.
But there is now concern that the election may be rigged.
"Things are not peaceful and quiet here. As long as the current administration is in power then we can only expect that they may forge the results," says Viktor Yushchenko, the main opposition leader.
Still looking facially disfigured, Mr Yushchenko claimed he was deliberately poisoned last month.
The authorities deny any involvement.
Mr Yushchenko says he was deliberately poisoned
But it become one of the talking points of the election.
The opposition leader is one of only two candidates thought to have a realistic chance of winning - the other is the Prime Minister Viktor Yanukovych,- who is backed by the outgoing president.
Around 100,000 opposition supporters gathered in the capital last weekend.
It was one of Ukraine's largest protests since independence.
But afterwards there were clashes between protesters and police.
Following the vote, it is predicted by the opposition that more than half a million people will attend a rally in Kiev.
Security has been stepped up across Ukraine for the election weekend.
The opposition claim there will be attempts to provoke violence, while the authorities accuse the opposition of plotting a revolution.
The prime minister, who says he believes there will be an honest vote, has called for calm.
"We must not gain power with violence; we can express our opinions only in a peaceful manner through the ballot box," said Mr Yanukovych.
The election will decide who replaces the outgoing president.
Leonid Kuchma has been in charge of the country for 10 years.
"No-one can say with certainty who will be the next president. This factor is a yardstick of how real democracy is in this country," President Kuchma said in an address on state TV on Friday.
"But this test is costing us dearly - we are paying the price of election tension."
A military parade in Kiev a few days ago demonstrated Russia's support for the prime minister as he shared the podium with President Vladimir Putin.
The prime minister and the pro-Western opposition leader are neck and neck in the opinion polls.
This election will decide whether Ukraine leans towards Russia or Europe.
But many Ukrainians are more worried about issues closer to home.
In a village outside the capital, babushka Galia feeds her pigs.
"It's all just a political game," she says.
Millions of voters like her live below the breadline.
They will be hoping that whoever wins the election will make tackling poverty their priority.