The two men contesting the presidency in Ecuador have ended their campaigning before a second round run-off vote.
Mr Noboa (left) has accused Mr Correa of planning insurgency
"Let every citizen be an electoral control centre," left-wing candidate Rafael Correa said, urging supporters to look out for electoral fraud.
His conservative rival, millionaire Alvaro Noboa, said Mr Correa planned to install a communist dictatorship.
The two men are running very close in recent opinion polls and correspondents say many voters are deeply disaffected.
Both candidates have promised to create new jobs, boost salaries and fight poverty and corruption.
A first round of voting in October failed to deliver a clear victor. The second round will be held on 26 November.
Ecuador is electing its eighth leader in a decade of political turbulence. The country's last three elected presidents were overthrown and only three since 1979 have succeeded in serving full terms.
Mr Noboa, Ecuador's richest man, held his final rally in his stronghold, the country's financial centre of Guayaquil.
He attacked his rival as a "communist" who wants "blood to run among the people".
"Correa wants an insurrection, a civil war in which the poor will die," Mr Noboa said.
At an earlier rally, Mr Noboa fell to his knees and pleaded with God to let him win on Sunday.
He has handed out money and gifts to supporters at many of his rallies.
He has also accused Mr Correa, a US-educated economist, of aiming to align Ecuador with Hugo Chavez's Venezuela.
Mr Correa and Mr Chavez are similarly scornful of the administration of US President George W Bush.
At his final rally, Mr Correa urged his supporters to follow the vehicles transporting ballot boxes to make sure votes were not tampered with.
"We have to defend the electoral victory, ensure there is no vote buying," he said.
An election win for Mr Noboa, he warned, would turn Ecuador into the banana magnate's "estate".