Afghanistan's presidential election is set to go to a second round run-off between former Foreign Minister Abdullah Abdullah and ex-World Bank economist Ashraf Ghani after none of the candidates won an absolute majority.
The vote will choose a successor to outgoing President Hamid Karzai in Afghanistan's first democratic transfer of power.
The eventual winner will have to oversee the fight against a resilient Taliban insurgency as 51,000 US-led troops depart this year, as well as strengthen an economy that relies on declining aid money.
"Based on our results, it appears that the election goes to the second round," Ahmad Yusuf Nuristani, head of the Independent Election Commission, was quoted by the AFP news agency as saying on Saturday.
Preliminary results showed Abdullah finishing top with 44.9 percent, followed by Ghani with 31.5 percent, and Zalmay Rassoul a distant third with 11.5 percent, according to the Independent Election Commission.
As no candidate gained more than 50 percent, a run-off between the two leading names is required under the Afghan constitution.
The final official result is set to be announced on May 14 after a period for adjudication of hundreds of complaints over alleged fraud.
A election chief told AFP a second round run-off would take place on June 7.
Eight men ran in the election, with polling day hailed a success by Afghan officials and foreign allies as the Taliban failed to launch a major attack despite threats to disrupt the vote.
"The election went pretty good, we are satisfied with it and I think we are prepared if it goes to the second round," Nuristani said.
Another expensive, and potentially violent, election could be avoided by negotiations between the candidates in the coming weeks, but Abdullah has dismissed talks of a possible power-sharing deal.
Ghani has also vowed to fight on in a run-off.
Serious fraud allegations are being investigated in the vote and Saturday's announcement is expected to be followed by fierce debate over disputed voting papers, ballot-box stuffing and other cheating allegations.
Preliminary results were delayed by two days due to fraud investigations, with officials vowing to sift out all suspect votes before they were counted.
Karzai, who has ruled since the Islamist Taliban regime was ousted in 2001, is constitutionally barred from serving a third term.
He pledged to stay neutral in the election, but was widely thought to have lent support to his loyal former Foreign Minister Zalmai Rassoul, who took just 11 percent of the vote.