What you need to know:
- The MDC, which had seven days in which to file its petition, arrived at the court less than an hour before it closed.
- Mnangagwa narrowly won the presidential race with 50.8 percent of the vote.
- But the court action is set to delay Mnangagwa's inauguration, scheduled for Sunday.
Zimbabwe's MDC opposition party lodged a court bid Friday to overturn the results of presidential elections that it alleges were rigged to ensure victory for Robert Mugabe's successor, Emmerson Mnangagwa.
The Movement for Democratic Change (MDC) has accused the ruling Zanu-PF party and the election commission of ballot fraud in the July 30 vote, Zimbabwe's first poll since the ousting of Mugabe in November.
"We will rest when this country is liberated," Jameson Timba, a senior member of the MDC, told journalists outside the Constitutional Court after party lawyers arrived accompanied by plastic boxes full of paperwork.
Party leader Nelson Chamisa tweeted: "Our legal team successfully filed our court papers. We have a good case and cause."
Mnangagwa, who is seeking to reverse Zimbabwe's economic isolation and attract desperately-needed foreign investment, had vowed the elections would be fair and fair, and would turn a page on Mugabe's repressive 37-year rule.
International monitors largely praised the conduct of the election itself, although EU observers said that Mnangagwa, a former long-time Mugabe ally, benefitted from an "un-level playing field" and some voter intimidation.
Mnangagwa narrowly won the presidential race with 50.8 percent of the vote — just enough to avoid a run-off against the MDC's Nelson Chamisa, who scored 44.3 percent.
The MDC, which had seven days in which to file its petition, arrived at the court less than an hour before it closed.
Analysts say that the legal challenge has little chance of success given the courts' historic tilt towards Zanu-PF, which has ruled since independence from British colonial rule in 1980.
But the court action is set to delay Mnangagwa's inauguration, scheduled for Sunday.
The court has 14 days to rule on the case, and could declare a winner, call another election, or order a run-off or recount, according to the Veritas legal group.
The inauguration should take place within 48 hours of the court's ruling, it added.
MDC party lawyer Thanbani Mpofu last week said that the Zimbabwe Electoral Commission's figures "grossly, mathematically fail to tally".
He said the party had evidence "for the purposes, not just of mounting a credible and sustainable challenge, but that will yield a vacation of the entire process."
The aftermath of the election has been marred by allegations of a crackdown on opposition members, including beatings and arrests.
On August 1, soldiers opened fire on MDC protesters, killing six people and sparking an international outcry.
Also on Friday, lawyers for senior opposition figure Tendai Biti asked judges to throw out charges against him over the protests against alleged election fraud, in a case raising further international concern about the new government.
Diplomats and election observers were present at the hearing in Harare after Biti fled to Zambia but was handed back to Zimbabwean police despite claiming asylum.
He faces charges of inciting the protests last week by proclaiming victory for the opposition.
"Zimbabwe faces a terrible threat from a group of people that has no respect for the law," Biti, who was granted bail Thursday, told the court.
Mnangagwa wrote on Twitter that Biti was released after he intervened personally in the case.
The Zimbabwe Human Rights Commission, established under the 2013 constitution, on Friday released a damning report into the post-election crackdown.
It said it had received numerous complaints of intimidation, often by men in military uniform, of voters thought to have backed the opposition.
"The ZHRC has established that there is hunting down and harassment of polling agents for independent candidates and opposition political parties," it said.
The EU, US, Canadian and Australian missions to Zimbabwe urged authorities to guarantee Biti's safety and human rights, and said they were "deeply disturbed by continuing reports that opposition supporters are being targeted by members of the Zimbabwean security forces".
The president, Zanu-PF and the electoral commission have denied all charges of cheating.