Francis recalled during an interview published Friday with the Barcelona newspaper "La Vanguardia," that Brazilian President Dilma Rousseff had asked him during a February visit to the Vatican to at least be neutral during the competition.
Laughing, Francis said: "The Brazilians asked for neutrality. I'll keep my word because Brazil and Argentina are always opponents."
On Thursday, Francis issued a video message pep talk to players and fans alike, urging them to make the World Cup a showcase for teamwork and solidarity and not an exhibition of racism, individualism and greed.
Argentina plays its first match Sunday, against Bosnia-Herzegovina.