Partial results in Peru's presidential election give former World Bank executive Pedro Pablo Kuczynski a narrow lead.
He had 50.82% against 49.18% for Keiko Fujimori, with 78% of votes counted.
Ms Fujimori had a strong lead ahead of the vote on Sunday but corruption scandals in her Popular Force party may have dented her support.
She is the daughter of Peru's former President, Alberto Fujimori.
He is in jail for crimes against humanity.
Ms Fujimori, 41, has said tackling crime is her priority.
She won the first round of voting in April.
The latest tally of votes is available at the ONPE website.
Mr Kuczynski, 77, who is an ex-Wall Street financier, said he would use his international financial experience to promote economic growth.
"We're going to have a government built on consensus. No more low blows or fights," he said, as the results started to come in.
Ms Fujimori won support from some Peruvians who credit her father with defeating the country's Maoist Shining Path rebel group in the 1990s.
But others say they would never support anyone associated with her father, who is serving 25 years in prison for ordering death squads to massacre civilians during his attempts to end the insurgency.
Mr Kuczynski is supported by the main opposition forces, including prominent figures such as left-wing former candidate Veronika Mendoza and the Nobel Prize winning novelist Mario Vargas Llosa.
But he has faced scrutiny over his close relationship to the Peru's business elite.
If he wins, he will become the oldest ever president of Peru at the time of taking office.
Some 23 million Peruvians were eligible to vote voted on Sunday's election to replace outgoing leftist President Ollanta Humala.