President Emmerson Mnangagwa denounced today actions against him by some members of the ruling Zimbabwe African National Union-Patriotic Front (Zanu-PF), warned of the possibility of their expulsion from the party.
Mr Chamisa wants Harare's constitutional court to declare him the victor or call a fresh election, it is reported.
"The inauguration is no longer going ahead as planned", Justice Minister Ziyambi Ziyambi said, after the opposition filed the challenge on Friday. "We have a good case and cause!"
"I am confident they have no case", ZANU-PF legal secretary Paul Mangwana said.
The opposition leader Nelson Chamisa, took to Twitter to confirm an appeal had been successfully filed. "The announcement made by ZEC chairperson Priscilla Chigumba was faulty, null and void at law", said Thabani Mpofu, a lawyer representing the MDC, soon after the filing of the party's legal challenge.
Mr Chamisa wants the court to declare him the victor or call a fresh election, his lawyer told Reuters news agency. Mugabe resigned in November after a military takeover, and many Zimbabweans were euphoric at his departure after decades of economic and political paralysis.
Two days after the vote, six people were killed in an army crackdown on protests against the victory by Mnangagwa's ruling ZANU PF party. He is facing charges of public violence and announcing false election results.
Foreign governments, Western election observers and human rights activists have expressed concern about the "excessive" force and reports of opposition supporters being targeted by security forces since then.
The protesters were disputing the election results.
We are also deeply concerned that Zambia chose to hand over former Minister of Finance Tendai Biti to the Zimbabwean authorities, and in the face of a reported Zambian court order blocking his expulsion from Zambia.