Copa America champions Uruguay slumped to their first defeat of the 2014 World Cup qualifiers on Friday as Colombia thrashed them 4-0.
Two-time world champions Argentina went top of the qualifying group with a convincing 3-1 home win over struggling Paraguay, for whom defeat saw them drop to the bottom of the table after six matches.
Atletico Madrid's much coveted striker Falcao got Colombia off to the ideal start against the Uruguayans with a goal in the second minute.
However, it was to be Teofilo Gutierrez who was to be the Colombians matchwinner as he struck twice in four minutes early in the second-half - Camilo Zuniga rounded off the stunning win in the final minute.
Uruguay coach Oscar Tabarez admitted Falcao's early goal had given the hosts the momentum that they needed.
"That goal calmed their nerves and put us as the away team into a difficult position," said Tabarez, who has in the past two years guided Uruguay to the World Cup semi-finals and then to the Copa America last year.
"We were always chasing the game throughout after that, though, I admit it is a shocking and disappointing result."
His Colombia counterpart, Argentinian Jose Pekerman was ecstatic at the outcome.
"Colombia can beat anyone, no matter what their stature, and they proved that today," said Pekerman, who coached Argentina at the 2006 World Cup.
"However, despite confirming that impression today (Friday), we will not slide into triumphalism."
Argentina too benefited from an excellent early start as Real Madrid wing Angel di Maria struck in the second minute and although Paraguay equalised from the penalty spot later in the half further goals by di Maria's clubmate Gonzalo Higuain and then superstar Lionel Messi rounded off the victory.
Victory sees Argentina go a point clear of Chile and Ecuador, who moved into third with a 1-0 win over Bolivia in Quito - Uruguay are two points adrift of Argentina in fourth.
"Our early goal was just the start we desired," said Messi.
"However, their penalty knocked us a little but we showed character to prevail in the end and now we are top of the group.
"However, that is all for nothing if we don't go on to win the World Cup and show we are the best in the world," added Messi, who craves a global title to put to an end the criticism he rarely shines for his country as he does for Barcelona.