Incumbent Dilma Rousseff will face Social Democrat Aecio Neves in a run-off vote on October 26 after they topped an Ibope Institute exit poll following Brazil's presidential election Sunday.
The exit poll showed Rousseff taking 44 percent of first round votes to 30 for Neves, leaving environmentalist Socialist Party candidate Marina Silva eliminated on 22 percent.
Silva, a former environment minister in Rousseff's Workers Party, had briefly topped second round projections after entering the contest in mid-August when running mate Eduardo Campos was killed in an air crash.
But Rousseff counter-attacked by accusing Silva, seeking to be her country's first black leader, of seeking to rein in some of the PT's flagship welfare programs which have lifted tens of millions out of extreme poverty over the past decade.
Neves, the favorite of a business community demanding root and branch economic reform, meanwhile sought to paint Silva, whom he trailed by 20 percent in projections four weeks ago, as a PT clone in debates just ahead of the vote.
Final opinion polls going into the weekend saw him finally overtake Silva -- though the pair remained in a technical dead heat.
But the exit poll showed him as pulling strongly away to secure a run-off berth.