Brazilian president Luiz Inacio Lula da Silva’s campaign accuses the US tech giant of election 'interference' in favour of right-wing challenger Flavio Bolsonaro (right) through alleged 'algorithmic manipulation'. (AFP pic)RIO DE JANEIRO: Brazilian president Luiz Inacio Lula da Silva will clash with his right-wing challenger Flavio Bolsonaro in a second and final televised debate on Friday, as both make a last-ditch effort to sway undecided voters.

The son of former far-right president Jair Bolsonaro beat Lula by two percentage points in the first round of presidential elections earlier this month, nabbing 47% of the vote.

The senator's surprise lead has kicked the Brazilian left into action, with enormous rallies staged across the country ahead of Sunday's runoff.