Ukraine's Supreme Court will hear a final appeal today against Western-leaning Mr Viktor Yushchenko's election as president.
Mr Viktor Yanukovich acknowledges he has little chance of overturning the result, however.
Today's hearing, forced by former Prime Minister Yanukovich who finished eight points behind in the December 26th ballot, is the last hurdle before Mr Yushchenko can take office after weeks of turmoil in the former Soviet republic.
The court has up to five days to consider the appeal, to be presented by Mr Yanukovich's team of Swiss and Ukrainian lawyers. The team is expected to argue the vote was subject to fraud and influenced by the "orange revolution" mass protests.
International monitors described the December election as a vast improvement over the previous month's poll - which they said fell far short of acceptable standards.