Nigeria began to announce early results on Sunday after a tight election for the presidency of Africa's most populous nation, as concerns grew over long delays in voting and accusations of attempts to manipulate tallies.
The election went ahead mostly peacefully, despite some ransacked polling stations and late starts at many others. Voters stayed up late at night in many locations to observe the count and "protect" the ballots.
Nearly 90 million were eligible to vote on Saturday for a successor to President Muhammadu Buhari, with many Nigerians hoping a new leader will do a better job tackling insecurity, economic malaise and growing poverty.
Independent National Electoral Commission (INEC) Chairman Mahmood Yakubu told reporters results would be officially announced state by state from Sunday when tallies are collated.
But slow uploading of results to INEC's online website provoked worries of electoral malpractice in a country with a history of ballot rigging and vote buying.
"Let Nigeria decide O! @inecigeria," Nigerian Afrobeats star and Grammy Awards winner Burna Boy wrote on Twitter. "No try any result magic."
The election pits former Lagos governor Bola Tinubu, 70, of the ruling All Progressives Congress (APC) against former vice president Atiku Abubakar, of the Peoples Democratic Party (PDP), 76.
But for the first time since the end of military rule in 1999, a surprise third-party candidate, Labour Party's Peter Obi, has challenged the APC and PDP dominance with a message of change.
PDP's candidate Abubakar urged INEC to upload the results immediately after accusing some state governors of trying to compromise the results.
"It will be a disservice to Nigerians and a negation to democracy for anyone to subvert the will of the people as freely expressed in their votes of yesterday," he said in a statement.
When he was defeated by Buhari in the 2019 election, Abubakar claimed massive fraud. The Supreme Court eventually tossed out his challenge.
Labour Party chairman Julius Abure also accused election officials of failing to upload results from parts of Lagos and southern Delta State to help ruling APC's candidate.
Observers group Yiaga Africa said it was "deeply concerned with the delay" in results.
But INEC said problems with uploading results on its IReV data page were due "technical hitches" and there was no risk of tampering.
"The commission wishes to assure Nigerians that the challenges are not due to any intrusion or sabotage of our systems," it said in a statement.
"It is important to avoid statements and actions that can heat up the polity at this time."
- 'Race is open' -
In Lagos and other cities, crowds stormed polling stations late on Saturday as electoral officials tallied the first results by hand and read out the counts before transmitting them to the central database.
On Sunday morning, people gathered at a newspaper stand in the Falomo area of Lagos, eager for results to come in and expressing hope this election would bring change.
"Last time, we knew Buhari was going to be re-elected, there was no excitement, but this time is so different, the race is open and there is hope," said mechanic Orubibi Dighobo.
Some polling stations were still voting early on Sunday after long delays getting started.
The commission has 14 days to officially announce results, but the online tally should be made available over the next few days.
To win the presidency, a candidate must get the most votes but also win at least 25 percent of votes cast in two-thirds of Nigeria's 36 states.
Some states are must wins. Lagos has the most registered voters at more than 7 million, followed by two states in the country's mostly Muslim north, Kano and Kaduna states.
The competitive race has some analysts forecasting an unprecedented runoff between the two frontrunners if no candidate meets election requirements. It would have to be organised within 21 days.
- Old guard rivals -
The success of Nigeria's vote will be closely watched in West Africa, where coups in Mali and Burkina Faso and growing Islamist militancy have taken democracy in the region back a step.
Buhari, a former army general, will step down after two terms in office. His critics say he failed in his key promises to make Nigeria safer.
Fuel and cash shortages at banks caused by a naira currency bill exchange programme in the run-up to the election also left many Nigerians struggling more than usual.
Whoever wins the election must quickly get to grips with Africa's largest economy and top oil producer, beset by problems from a grinding jihadist war in the northeast to double digit inflation.
APC's candidate Tinubu, a long-time political kingmaker and southern ethnic Yoruba Muslim, says "It's my turn" for the presidency. He says his experience as Lagos governor will count.
He faces a familiar rival -- PDP candidate Abubakar, a Muslim from the northeast who is on his sixth bid for the top job and touts his business experience to fix the economy.
By By Camille Malplat With Louise Dewast In Port Harcourt