People in Mali are voting in a presidential election run-off.
Many expect Former Prime Minister Ibrahim Boubacar Keita, who won 40% of the vote in the first round, to defeat ex-Finance Minister Soumaila Cisse.
The election follows more than a year of turmoil which included a coup and a French-led military intervention to oust Islamist rebels from the north.
The victor will oversee more than $4bn (?2.6bn) in foreign aid promised to rebuild the West African state.
A 12,600-strong United Nations Stabilisation Mission in Mali (Minusma) is currently deploying, as France begins to withdraw its 3,000 troops.
The UN has stressed the importance of the election to the restoration of constitutional order and the start of national dialogue and reconciliation.
A record 49% of the 6.8 million registered voters cast a ballot in first round on 28 July.
Mr Cisse, who was second among the 27 candidates with 19.7% of the vote, complained that there was widespread fraud, with more than 400,000 ballots declared spoiled.
However, Mali?s Constitutional Court rejected the allegations and the head of the EU election observer mission, Louis Michel, praised the electoral process for its transparency.
Ahead of Sunday?s second round, for which some 21,000 polling stations opened across Mali at 08:00 GMT, Mr Michel said he had been ?positively surprised? by preparations.
Mr Keita ? who is popularly known by his initials, ?IBK? ? has urged voters to give him what he called a ?clear and clean? majority in the run-off.
?My first priority would be the reconciliation of the country. After the trauma that it has suffered, a new start is needed,? he told reporters on Saturday.
But Mr Keita also said he would be pursuing ?a real peace? not a false one?.
The 68-year-old has the support of influential moderate Islamic leaders, and 22 of the 25 losing first-round candidates have given him their backing.
Mr Cisse, 63, has run on pledges to improve education, create jobs and reform the army. He has been more openly critical of the leaders of last year?s military coup than Mr Keita.
?I am confident, because it is not about adding to the votes from the first round, there will be new votes, it is a new election,? he told the AFP news agency on Saturday. ?Everything restarts from zero.?
The BBC?s Mike Wooldridge says a ceasefire that is allowing voting to take place in northern Mali also obliges a new government to open peace talks with the separatist Tuareg rebels within two months.
Much is therefore at stake in the election, not least its potential to unlock billions of dollars in aid promised by international donors, he adds.