Conservative millionaire Sebastian Pinera, 60, and ruling-party candidate Eduardo Frei, 67, on Sunday led the first round of Chile's presidential election, according to preliminary official results, dpa reported.
Pinera got 44.23 per cent of the votes to Frei's 30.50 per cent, with more than half the ballots counted, Chile's electoral authorities said.
If the final results confirm this trend and none of the candidates gets more than half the votes, then Pinera and former Chilean president Frei (1994-2000) would clash in a runoff vote January 17.
The runoff could turn out to be historic as the ruling Concertacion - a coalition of Socialists and Christian-Democrats with two smaller parties that has ruled Chile since the restoration of democracy in 1990 - could lose power, despite the huge popularity of outgoing President Michelle Bachelet.
According to preliminary official results, independent leftist Marco Enriquez Ominami got 19.39 per cent of the votes, to leftist Jorge Arrate's 5.86 per cent.
Earlier projections made by the private Diego Portales University - based on a quick count of votes from 85 polling stations - also said that Pinera fell short of an outright victory and was set to clash with centre-left candidate Frei in the runoff.
"Pinera is very happy and grateful for the huge support he got from Chileans," his advisor Senator Andres Allamand told reporters. He described the major lead over second-placed Frei as "extraordinarily comfortable."
Even before Sunday's election, there had been talk of a union of the Chilean left ahead of the runoff, to prevent the right from getting power in Chile through democratic means for the first time since 1958.
With about 8 million Chileans registered to vote, the first polling stations closed at 2000 GMT Sunday.
The preliminary results confirmed the projections of opinion polls prior to the election. Pinera was widely regarded as the favourite to win the first round of voting.
"A message of hope for all Chileans: Better times are coming for Chile and for Chileans," Pinera said as he cast his ballot.
Bachelet, the first Chilean woman ever to hold the presidency, has an approval rating of almost 80 per cent as she approaches the end of her four-year mandate. Chilean law forbids immediate re-election, but observers think Bachelet will target a return in 2014.
"Chile will as always show the world that it is a country that respects democracy, that respects peace," Bachelet said as she cast her ballot.
Analysts blamed the Concertacion's poor performance on the long period in government, internal divisions and Frei's perceived lack of charisma.
Still, no dramatic changes were expected even if the right were to win the runoff. The campaign has lacked major differentiation on economic policy, with the main candidates promising to fight inequality, improve access to education and new jobs.
In terms of foreign policy, Pinera might seek closer relations with the United States and other Latin American countries governed by the right, such as Mexico and Colombia.
Differences widen over Chile's difficult history, particularly the issue of punishment for military and police officers implicated in human rights abuses during the Augusto Pinochet dictatorship. Another bone of contention has been reform of the constitution, a Pinochet- era relic.
Pinera opposes both human rights prosecutions and constitutional changes.
Bachelet's successor is to be inaugurated for a four-year term on March 11.