Brazil is heading for a presidential run-off after right-wing Senator Flávio Bolsonaro finished ahead of incumbent President Luiz Inácio Lula da Silva in the first round, but failed to secure the majority needed for an outright victory.
With almost all votes counted, Bolsonaro had about 47% of the vote, compared with roughly 45% for Lula.
The two candidates will now face each other again on 25 October to decide who will lead Latin America's largest country and economy.
Flávio Bolsonaro, 45, is the son of former President Jair Bolsonaro, who was convicted and is serving a 27-year prison sentence over his role in plotting to overturn the 2022 election result.
Flávio has campaigned on promises including tougher action on crime and closer relations with the United States.
The first-round result came despite polls in the final days of the campaign generally showing Lula ahead.
Bolsonaro's stronger-than-expected performance has reshaped the contest, while voters who supported the other candidates in the first round could now play an important role in determining the outcome.
The election is also taking place amid a broader shift to the right across parts of Latin America.
Brazil's result will therefore be closely watched beyond its borders, particularly because of the country's size, economic influence and relationship with the United States.
After casting his ballot, Lula, 80, framed the election as a choice between strengthening democracy and what he called "barbarism." Bolsonaro, meanwhile, said he wanted to bring change and give Brazilian families a new opportunity to dream.
The second round on 25 October will determine whether Brazil remains under Lula's left-wing leadership or shifts towards the right under Flávio Bolsonaro.
