Sebastian Pinera is reportedly leading the count
Centre-right candidate Sebastian Pinera has won the first round of Chile's presidential election, but without the majority needed to avoid a run-off.
The billionaire businessman has 44% of votes, with the count almost complete, below the 50% required for victory.
He will now face centre-left candidate Eduardo Frei, a former president himself, in a second round in January.
A victory for Mr Pinera would put conservatives back in power in Chile after 20 years of centre-left rule.
CHILE'S PRESIDENTIAL HOPEFULS
Sebastian Pinera - centre-right businessman, lost to Michelle Bachelet in 2006 presidential race
Eduardo Frei - candidate of the ruling centre-left coalition; served as president 1994-2000
Marco Enriquez-Ominami - independent set to split centre-left vote; former film director
Jorge Arrate - veteran Socialist, has support of Communist Party
Mr Frei, 67, is seeking his second term as president after an absence of 10 years.
Around eight million Chileans have been voting in the election.
Mr Pinera, 60, owns a television channel, a stake in Chile's most successful football club and has millions of dollars in investments.
He has campaigned on a tough law-and-order ticket and has also vowed to use his business know-how to reactivate the economy, promising Chileans an annual growth rate of 6% for the next four years.
The BBC's Gideon Long in Santiago says a victory for Mr Pinera would give Chile its first conservative government since 1990, when strongman Gen Augusto Pinochet finally relinquished power.
The poll could lead to a run off in January.
This is the second time Mr Pinera has run for the presidency at the head of a centre-right coalition.
In 2006, he lost to the extremely popular outgoing Socialist president, Michelle Bachelet.
But under the constitution she cannot stand for re-election, and her candidate, Mr Frei, is struggling to emulate her popularity.
The third candidate was Marco Enriquez-Ominami, a 36-year-old independent who has emerged from nowhere and split the centre-left vote.
He says Chile needs a new face and new ideas in the presidential palace, after two decades of the same coalition.
The fourth candidate was Jorge Arrate, a veteran Socialist who has the support of Chile's Communist Party.
Mr Enriquez-Ominami polled 20%, with Mr Arrate on 6%.
If Mr Pinera is successful, it will mark the first time in 51 years that the conservatives have taken power in Chile via the ballot box.