DR Congo was on Monday making plans to install Felix Tshisekedi as its new president this week after a long and bitter election whose outcome was disputed by the runner-up and shunned by many western nations.
The ceremony, which looks likely to happen on Thursday, will see the 55-year-old sworn in as president, replacing Joseph Kabila who has ruled DR Congo since 2001.
The inauguration looks set to draw a line under three weeks of growing tension over the long and drawn-out counting process after the December 30 vote, which provisionally declared Tshisekedi, one of two opposition candidates, the winner.
But the outcome was swiftly denounced by his opposition rival Martin Fayulu, who filed an appeal. He claimed he had been cheated of an outright victory by an "electoral coup" masterminded by Kabila with Tshisekedi's approval.
Although leaked figures from the provisional count appear to be heavily in his favour, the Constitutional Court dismissed his appeal.
At stake is political stewardship of the mineral-rich but notoriously unstable central African nation.
Democratic Republic of Congo has a population of some 80 million and covers an area the size of western Europe.
Ahead of this week's ceremony, tension was on Monday building in the capital.
Some 300 Fayulu supporters clashed there with motorbike taxi drivers whom they took for Tshisekedi supporters, leaving one driver nursing a serious head injury, an AFP correspondent said.
Several journalists were also hurt in the fracas. The Actualite news website said one of its reporters was "assaulted by police", while others were attacked by Fayulu supporters who accused them of being pro-Tshisekedi.
Although the ceremony had been due to take place on Tuesday, a spokeswoman for the Cach opposition coalition that backed Tshisekedi said it was likely to happen on Thursday.
Jean-Pierre Kambila, a senior figure in Kabila's outgoing cabinet, said the date would be settled later in the day.
Without a firm date, officials have been unable to send out invitations to foreign heads of state and government — and given the very public dispute over the result, it remains to be seen who will actually turn up.
The court's dismissal of Fayulu's appeal and its subsequent confirmation of Tshisekedi as president-elect has divided sub-Saharan Africa.
The 16-nation Southern African Development Community congratulated Tshisekedi, as did Kenya.
But the result won a mixed reception among the nine nations bordering DR Congo.
Burundi and Tanzania, who are working with Kinshasa to fight rebels on their common border, sent congratulations, while Republic of Congo, Uganda, Rwanda, Zambia and Angola remained silent.
Fayulu, who has declared himself "president-elect", has urged the international community not to formally recognise Tshisekedi.
"I urge the African presidents who asked the Congolese people to respect the Constitutional Court's decision, to respect the sovereign decision of the Congolese people who elected me president with more than 60 percent of the vote," he wrote on Twitter.
"We should not encourage fraud, lies and falsehood," he said.
The AU had expressed "serious doubts" about the provisional result and urged the court to delay its announcement pending a visit by its chairman, Rwanda's Paul Kagame, and AU Commission president Moussa Faki on Monday.
But the weekend announcement caught the AU off guard, sweeping aside its concerns and prompting it to "postpone" the visit.
The European Union had also expressed reservations, saying "doubts remain regarding the conformity of the result".
And France, which had openly disputed the provisional results, issued a low-key statement saying it "noted" Tshisekedi's victory.
"This election allowed the Congolese people to strongly and calmly voice their desire for change," the foreign ministry said, indicating the French ambassador would attend the ceremony.
"We hope the new president knows how to respond to this and we call on him to hold dialogue with the rest of country's political actors to achieve that end."
DR Congo's influential Roman Catholic Church has dismissed the official result, saying it "does not correspond" with data collected by its 40,000 election monitors.
On paper, at least, DR Congo appears to be going through its first-ever peaceful handover of power since independence from Belgium in 1960.
The president-elect, who has never held high office, is the son of DR Congo's Etienne Tshisekedi, a veteran politician who founded the country's oldest and largest opposition party.
In recent decades, DR Congo has lived through two regional wars (1996-97 and 1998-2003) with the last two presidential elections, in 2006 and 2011, marred by bloody clashes.