Ukraine's Supreme Court has begun to hear the closing arguments in a case that could lead the way to a resolution of the political dispute.
Tens of thousands of opposition supporters rallying in Kiev's main square have been watching the court deliberations on giant television screens.
Both the opposition and the Government-backed presidential candidate have asked the court to annul last month's vote, each claiming the other rigged the ballot.
The 21-judge panel will hear final statements from representatives of the two rivals and the electoral commission.
A ruling is expected in the next 24 hours.
By Emma Griffiths 3 December 04
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