Flavio Bolsonaro has led in polls since the first round, but his lead narrowed slightly in two polls this week, which showed him with 51% of voting intentions compared with 49% for Luiz Inacio Lula da Silva. (AFP pic)RIO DE JANEIRO: After a day of energetic rallies by their supporters, Brazil's leftist President Luiz Inacio Lula da Silva and right-wing senator Flavio Bolsonaro will go head-to-head Sunday in their first debate, a week ahead of a bitter and divisive presidential runoff.

Bolsonaro, 45, son of the far-right former president Jair Bolsonaro, secured a shock first-round lead over Lula earlier this month, defying poll predictions.

The televised debate on Sunday evening is expected to be pivotal in an election race marked by scandals and insults that is likely to go down to the wire.