Former Maldivian President Mohamed Nasheed was leading the bitterly contested election, but could face a tricky run-off, preliminary results showed.
Official results after more than three quarters of the ballots had been counted gave Nasheed a clear lead with 44.94 percent of the popular vote.
His closest rival, Abdulla Yameen, the half brother of former autocrat Maumoon Abdul Gayoom, garnered 31.34 percent of the vote with third candidate and business tycoon Qasim Ibrahim trailing with 23.72 percent.
The Elections Commission (EC) said it expected final results around midnight (19:00 GMT).
If no candidate wins an outright majority, more than 50 percent of the vote, the EC has said there would be a run-off election on Sunday.
However, there were doubts over the second round with Chief Elections Commissioner Fuwad Thowfeek saying that the second and third placed candidates were yet to endorse voter lists for Sunday's vote, a requirement ordered by the Supreme Court.
In a late development Saturday, a member of candidate Qasim Ibrahim's Jumhoory Party also filed a lawsuit asking the Supreme Court to delay the runoff, citing the inability to campaign for a second round.
This was the country's third bid in two months to choose a new president and end a political crisis sparked by the toppling of their first freely-elected leader nearly two years ago.
Low voter turnout
Voter turnout on Saturday appeared to be less than a previous vote in September, the result of which was annulled by the Supreme Court. About 240,000 people were eligible to vote.
The Indian Ocean archipelago, a popular tourist destination, has been the focus of intense diplomatic pressure since last the results of last polls cancelled.
A previous round of elections scheduled for October 19 was scuttled by police saying that the same two candidates, Yameen and Ibrahim, had not approved the electoral roll and therefore the ballot could not go ahead.
Western and Asian diplomats monitoring Saturday's vote said it had gone off well without any incidents, but they feared there could be obstacles for Sunday's run-off if no one gets a majority.
Saturday's vote appeared to be a repeat of the September 7 vote which was rescinded by the court following allegations that flawed voter lists had been used, although international observers had given it a clean chit.
In that election, Nasheed had secured 45 percent of the vote, but not enough to win in the first round. Yameen had 25 percent and Ibrahim 24 percent.
Outgoing President Mohamed Waheed, who is not contesting, got five percent of the vote in September.