Russian opposition leader Aleksei Navalny is holding the final rally of his campaign for Moscow mayor.
Navalny's campaign office said some 15,000 people gathered at Moscow's central Sakharova Avenue, where the rally kicked off with a rock concert on September 6.
Navalny told the crowd the election campaign had been unfair, and accused the authorities of planning to rig the election.
He said he wouldn't "watch impassively" if the authorities falsify the vote.
The Kremlin-backed incumbent, Sergei Sobyanin, held a rival rally in Moscow the same day.
Muscovites go to the polls on September 8 to elect a mayor for the first time in a decade after regional elections were reinstated.
Navalny is seen as the main challenger to Sobyanin, who is expected to secure reelection in the first round.
Navalny is predicted to take second place with 18 percent of the vote.
In June, Navalny was sentenced to five years in prison on fraud charges he rejects as politically motivated.
He was released pending appeal.
Based on reporting by Interfax, AFP, and Tvrain.ru