Nigerian President Goodluck Jonathan and presidential candidate of the ruling People's Democratic Party (PDP) embraces leading opposition All Progressive Congress presidential candidate Mohammadu Buhari during a conference to promote non-violence att ~ STRINGER
Lagos - Africa's most populous country and top economy, Nigeria, holds general elections this Saturday -- the fifth since civilian rule was restored in 1999.
Here are five key figures whose actions could shape the outcome of the vote and its aftermath.
Nigeria's 57-year-old leader is seeking a second term after a tumultuous five years plagued by the dramatic rise in strength of Boko Haram extremists and a widely criticised job performance.
Critics say he has failed to tackle corruption or improve infrastructure, especially electricity supply, but Jonathan still has supporters, particularly in the mainly Christian south of the religiously divided nation.
Nigerians have never seen power change hands through the ballot since independence from Britain in 1960 but Jonathan has repeatedly vowed to respect the will of the voters.
If the election tilts in the opposition's favour, all eyes will be on the president to see if he keeps that promise.
Also read: Jega urges election observers to abide by guidelines
The former military ruler is taking his fourth shot at the presidency since democracy was restored in 1999, and has tried to position himself as Nigeria's top anti-corruption crusader.
Buhari, 72, insists he will win this time, refusing to even discuss the prospect of another defeat.
If Jonathan is declared the winner, Buhari's actions could prove crucial in avoiding widespread post-election unrest.
Experts say the predominantly Muslim north is a tinderbox that may explode if Buhari, the region's favourite son, is perceived as having been cheated out of an electoral win.
Buhari's moves as the results come in will therefore be closely watched.
Boko Haram's leader, a wanted criminal who is suspected of orchestrating crimes against humanity, has vowed to disrupt the polls, which the Islamist group views as "un-Islamic".
That sinister pledge may turn out to be empty bluster but given Boko Haram's proven ability to sow chaos across northern Nigeria, the possibility exists of widespread attacks, including bombings, on polling day.
The head of Nigeria's Independent National Electoral Commission (INEC) has faced fierce criticism from both the opposition and the ruling party during the campaign.
But impartial observers broadly see him as tough-minded, independent administrator committed to overseeing a fair and credible vote.
The career academic cut his political teeth opposing the brutal military dictatorship of Sani Abacha in the late 1990s.
Given his background, most experts believe Jega will seek to declare an accurate result as quickly as possible, regardless of any political interference he may face.
The independence of Nigeria's military and police around election day will likely be crucial in ensuring the vote is respected nationwide.
The defence ministry has issued clear statements declaring itself to be a completely non-partisan actor in the polls but troubling events in recent months have raised concern.
Officers, believed to be from the police force, fired teargas on senior opposition lawmakers as they tried to enter parliament for a key vote in November.
The opposition has specifically identified the police chief in the capital Abuja, Joseph Mbu, as being an outspoken loyalist of the ruling party.
Observers say that avoiding confrontation between the security services and political demonstrators should be a top priority.