Nigeria's outsider candidate Peter Obi won the key state of Lagos on Monday as early results emerged from the tight race for the presidency of Africa's most populous nation.
The Lagos win by Labour Party's Obi underscored his surprise challenge to ruling All Progressives Congress (APC) and main opposition Peoples Democratic Party (PDP), which have governed Nigeria since the end of military rule in 1999.
The closely fought race pits Obi against two old-guard rivals: APC's Bola Tinubu, 70, a former Lagos governor, and PDP's Atiku Abubakar, 76, a former vice president on his sixth bid at the presidency.
Nearly 90 million were eligible to vote Saturday for a successor to President Muhammadu Buhari, with many hoping a new leader can bring real change to tackle insecurity, economic malaise and widening poverty.
With more than seven million registered voters, Lagos is a key state. It is also the bastion of APC's Tinubu, who governed Lagos from 1999 to 2007.
The Independent National Electoral Commission (INEC) said Obi won more than 582,000 votes against around 572,000 for Tinubu.
Obi, 61, a former Anambra State governor, has attracted younger voters with a campaign message of change from his two septuagenarian rivals.
Tinubu known as the "Godfather of Lagos" for his influence, accepted defeat and urged his supporters to remain calm.
"As a democrat, you win some, you lose some," he said.
Voting on Saturday was mostly peaceful, although thugs ransacked some polling stations and many others opened late.
The slow pace of the state-by-state count and accusations of manipulation have fuelled tensions.
By early Monday evening, INEC had only released official results from 10 of Nigeria's 36 states and the final count could take longer.
Tinubu had won western Kwara State and his stronghold southwestern states of Ondo, Oyo, Ogun and Ekiti while PDP's Abubakar won Osun state and the northeastern states Yobe and Gombe.
As well as Lagos, Obi had won Enugu in the southeast where he has strong support.
"I wouldn’t overstate the importance because it's so close. Ten thousand votes are not enough to sway the election nationally," Eurasia Group analyst Amaka Anku told AFP of Obi's Lagos win.
"What’s important to see now is how well Tinubu is doing across the north."
Two-thirds rule
To win the presidency, a candidate must garner the most overall votes along with 25 per cent of ballots cast in two-thirds of Nigeria's states - a measure to reflect the country split between a mostly Muslim north and widely Christian south, and with three main ethnic groups.
Voting is determined by large key states including Lagos, northwest Kano, Kaduna and Southern Rivers.
Votes for the presidency are tallied by hand at local polling stations and results are uploaded online to INEC's central database IReV, which is meant to improve transparency.
But slow uploading of results generated worries about malpractice in a country with a history of ballot rigging and vote buying.
PDP and Labour on Monday accused the ruling APC of pressuring INEC officials over results.
INEC said Sunday problems with uploading results were due to "technical hitches" and there was no risk of tampering.
An EU observer mission said INEC "lacked efficient planning and transparency during critical stages" and reduced public trust with delays in voting and results.
The vote in Africa's biggest democracy is being closely watched in a region battered by coups in Guinea, Burkina Faso and Mali, and growing Islamist militancy.
Tinubu, a southern Yoruba Muslim, and Abubakar, from the northeast, are long-time political fixtures who have fought off past corruption accusations. But the emergence of Obi - a Christian ethnic Igbo from the southeast - threw the race open.
Some analysts are forecasting a runoff between the two frontrunners if no candidate meets election requirements - a first in Nigeria's history. It would have to be organised within 21 days.
Buhari, a former army general first elected in 2015, will step down after two terms in office. His critics say he failed in his key promises to make Nigeria safer.
Whoever replaces him must quickly get to grips with Africa's largest economy and top oil producer, beset by problems including a grinding jihadist war in the northeast and double-digit inflation.