Early results have started to arrive from Nigeria’s tightest election since the end of military rule in 1999.
Official results from the south-western Ekiti state show a clear victory for ruling party candidate Bola Tinubu in one of his strongholds.
Following widespread delays and attacks on some polling stations on Saturday, voting was postponed until Sunday in parts of the country so final results will take some time.
Turnout appears to be high, especially among young people who make up about a third of the 87 million eligible voters.
This makes it the biggest democratic exercise in Africa.
The election has seen an unprecedented challenge to the two-party system that has dominated Nigeria for 24 years.
Peter Obi from the previously little-known Labour Party, Bola Tinubu from the ruling All Progressives Congress (APC) and Atiku Abubakar of the main opposition Peoples Democratic Party (PDP) are all seen as potential winners. There are 15 other presidential candidates.