A tribunal has begun hearing a petition by several opposition candidates in Nigeria to annul Bola Tinubu's victory in February's presidential election.
Peter Obi and Atiku Abubakar are challenging Mr Tinubu's victory on several grounds - including the fact that the Independent National Electoral Commission (Inec) failed to upload the result on its website portal in real-time.
They allege that this was in breach of the Electoral Act, and Inec's promise to ensure transparency.
Inec is defending the case, saying the final result reflected the will of the electorate and delays in uploading the results were caused by technical glitches and a spike in traffic.
Mr Obi - who contested the presidency for the first time, and had been popular among young voters in the south - was in court for the start of the case.
At least three other opposition figures have thrown their weight behind the bid to overturn the result.
A verdict is not expected before Mr Tinubu's inauguration on 29 May.
He was officially declared the winner with 37% of the vote, with Mr Abubakar polling 29%, and Mr Obi 25%.
Mr Tinubu - a member of the ruling party - will succeed President Muhammadu Buhari, who is stepping down at the end of his two terms.
Source: BBC
