A run-off in East Timor's presidential election looks set to be contested by the current prime minister and a candidate of the ruling party.
Francisco "Lu-Olo" Guterres appears to have won most votes
With 70% of the votes counted, PM Jose Ramos-Horta was trailing the Fretilin Party's Francisco Guterres by about 5%, election officials said.
Five other candidates are alleging discrepancies in the voting.
Monday's presidential election was East Timor's first since it won independence from Indonesia in 2002.
Many are hoping the vote will resolve the political tension and instability in the young country, which resulted in clashes last summer between rival military factions that left 30 people dead.
Analysts hope the prospect of a repeat vote will not trigger violence, but similar fears of unrest during the first round mostly proved unfounded.
The national election commission said that, with 70% of ballots counted, Mr Guterres - popularly known as Lu-Olo - of the powerful Fretilin party had secured 29% of the vote.
Mr Ramos-Horta had taken 23%, with the Democratic Party's Fernando de Araujo in third place with 19%.
With no candidate getting the 50% of votes needed to win outright, a run-off is expected to be held on 8 May.
"The most probable situation is Mr Lu-Olo and Mr Ramos-Horta will go to the second round," election commission spokesman Martinho Gusmao said.
Mr de Araujo was among five presidential candidates who filed a formal protest over the election, alleging discrepancies between the number of votes and voters.
"There are a lot of irregularities in this process and we want to tell the public we are not happy," Mr de Araujo said.
Mr Ramos-Horta, who won the Nobel Peace Prize for championing East Timor's independence cause, is running as an independent.
He has the support of outgoing President Xanana Gusmao, who hopes to run for prime minister later this year.
Mr Gusmao won the presidential election held just before independence was formally declared in 2002 but did not stand for re-election as president this year.
They are trying to oust the traditionally popular Fretilin party from power.
Both the EU and the UN praised the election, saying it had run smoothly for the most part and there had been a high turnout.