STORY: Bola Tinubu was sworn in as Nigeria's president on Monday (May 29) following a disputed election.
He faces pressure to quickly improve economic and security conditions.
Many complain the economy worsened under his predecessor, former military ruler Muhammadu Buhari.
Tinubu will inherit anaemic growth, record debt and shrinking oil output.
Two of Tinubu's main opponents in the February election are challenging his victory on the basis of fraud claims.
A tribunal will start on Tuesday (May 30) to hear their main arguments.
Opponents see Tinubu as a member of the old guard.
A member of Buhari's party, the former Lagos state governor has long exerted influence from behind the scenes.
The election had galvanized young voters hoping for a break from the two parties that have dominated Nigerian politics since military rule ended in 1999.
But what authorities promised would be the country's freest and fairest election yet ended in frustration for many.
Tinubu won with 37% of the vote, the lowest share since 1999.