(AFP) - Brazil entered the final stretch of a deeply polarized presidential race Monday after an inconclusive first voting round put far-right incumbent Jair Bolsonaro in an unexpectedly strong position.

Bolsonaro, 67, garnered 43 percent of Sunday's first-round votes compared to 48 percent for leftist frontrunner Luiz Inacio Lula da Silva -- a five-point difference.

Polls had predicted a much larger gap of 14 points, recalling the surprises of Brexit and Donald Trump's US election win in 2016.

Ex-president Lula, 76, had appeared to be within arm's reach of taking the election in the first round with more than 50 percent of the vote -- but the race now heads to an October 30 runoff.

Not only did Bolsonaro surpass expectations, but many of his allies performed better than polls predicted in congressional and gubernatorial races.

Despite finishing second, Bolsonaro sounded triumphant.

"Our adversaries prepared for a 100-meter sprint. We're ready for a marathon," he wrote on Twitter Monday.

"We're confident we're going to win, for God, country, family, life and liberty!"

Bolsonaro proved his movement remains a major force despite the controversies of his four-year tenure, marked by a shocking pandemic death toll blamed in part on his Covid-skeptic policies, surging destruction of the Amazon rainforest and a sharp rise in the number of Brazilians living in hunger.

The Sao Paulo Stock Exchange reacted to the first-round results in Latin America's largest economy with a 5.5 percent rise in afternoon trading Monday.

Analysts said the market welcomed the strong showing from fiscal conservatives.

"No matter who wins the runoff, he'll have to govern with a more right-wing, liberal, free-market Congress," said economist Igor Macedo de Lucena.

- 'The fight continues' -

Both men declared themselves ready for the final push to attract the votes of some nine million Brazilians who cast their ballot for minority candidates -- none of whom managed to break through five percent of support -- and 31 million others who did not vote at all.

Lula, who wasted no time holding a strategy meeting with his campaign team Monday, said: "We have to talk to all the people who didn't vote for us in the first round."

He added he was "ready to talk with the whole world" and said he was committed to forming a "bloc of Democrats" to defeat Bolsonaro.

"The deepest change in the country has already begun! It is not the people who have to fear," Lulu said on Twitter.

Analysts say Bolsonaro's performance bodes for a stressful and divisive four weeks ahead.

The incumbent has repeatedly sought to cast doubt on Brazil's electronic voting system and questioned the validity of opinion polls placing him a distant second.

Now, he can argue that Sunday's results bear out his claims.

- 'Emboldened' -

Bolsonaro's rhetoric has raised fears he could trigger a Brazilian version of the riots in January last year at the US Capitol after former president Donald Trump refused to accept his 2020 election defeat.

Bolsonaro "will be very emboldened," by Sunday's electoral performance, said Michael Shifter of the Inter-American Dialogue think tank.

"He's beaten the expectations.... He will play on that the experts were wrong: 'I've got the momentum and I'll defy expectations again in the second round'."

Passions will be high on both sides.

Bolsonaro now has "an extra month to cause turmoil in the streets," political scientist Guilherme Casaroes of the Getulio Vargas Foundation's (FGV) Sao Paulo School of Business Administration told AFP.

"Any kind of doubt that he casts upon the electoral system will work in his favor... demobilizing voters not to go vote for Lula" -- who left office after two terms in 2010 with an unprecedented 87-percent approval rating and is credited with helping lift 30 million people out of poverty.

Bolsonaro will continue hammering on Lula's flaws, including his conviction for corruption -- since overturned in court but not in the court of public opinion, analysts say.

"Lula's chances of being elected seem considerably slighter," said Casaroes.

As for Bolsonaro, it now appeared he "could make this a contest," said Shifter.

"Instead of the great comeback (for Lula) it could be the great upset."

© Agence France-Presse