Alexei Navalny, the Russian opposition activist, has filed a lawsuit of more than 50,000 pages of documents at a Moscow courthouse.
The case, filed on Thursday, challenges the results of the city's mayoral election, which he lost to the Kremlin-backed incumbent.
Navalny claims there were violations at the polls and throughout the election campaign.
The court will decide within several days whether to accept the case.
Navalny took 27 percent of the vote in Sunday's election against incumbent Sergei Sobyanin's 51 percent.
If Sobyanin had taken less than 50 percent, he would have been forced into a run-off against Navalny.
"We don't recognise the results of the elections," Navalny said outside court, surrounded by boxes of paperwork supporting his claim.
But President Vladimir Putin, speaking at Sobyanin's inauguration on Thursday, said the vote was a "free, absolutely competitive contest".
Sobyanin did not run as strongly as pollsters and administration officials expected.
Navalny's campaign has accused the mayor's office of falsifying the results.
In particular, he zeroed in on the unusually high number of "voters from home" people too sick or old to make it to the polls.
Navalny claimed many of them had been encouraged to cast their ballots despite not properly registering.
Golos, the independent election monitor, has supported Navalny's calls for a recount.
The group said it saw no widespread vote-rigging in the city but had concerns about issues such as voting from home, which could have tipped a close race just enough in Sobyanin's favour.
Navalny, who still faces up to five years in prison on embezzlement charges, has urged his supporters to protest peacefully and legally against the election result.