Brazilian side Gremio beat Uruguay's three-time Copa Libertadores winners Nacional 1-0 in their opening Group 6 match.
The only goal at the Parque Central stadium came in the 68th minute when Ramiro found space on the right and teed up the chance for Christian Riveros, on the stretch, to apply the clinical headed finish. Man of the match Edinho savoured Gremio's away victory, saying: "It is very difficult to play here. Our squad did not feel the pressure. We are very satisfied because we could get a great result far from home."
His team-mate, defender Werley, added: "We faced a tough opponent but I think we were superior for most of the game. We scored and then closed our lines to secure the result. At the end, we suffered pressure but managed to resist."
Nacional boss Gerardo Pelusso felt his team were hard done by, saying: "If there was justice we deserved a draw."
In the same group, Colombian side Atletico Nacional won 1-0 at home against Argentinian outfit Newell's Old Boys. Edwin Cardona fired the 80th-minute winner, with his strike from outside the penalty area squeezing into the right corner.
In Group 5, Universidad de Chile saw off Uruguayan side Defensor Sporting 1-0 thanks to Gustavo Lorenzetti's 82nd-minute goal. Universidad manager Cristian Romero said: "It was reward for the team that was really looking (for a goal). In the end, we cornered Defensor and we even had chances to add to our score. We needed to show patience more than speed and the players understood it."
Former Brazil and Inter Milan striker Adriano made his return to action after almost two years out of the game as Atletico Paranaense beat Bolivian side The Strongest 1-0. The only goal of the Group 1 game came after 23 minutes when Sueilton's long ball was headed in by fellow defender Paulinho Dias.
Adriano, whose off-field lifestyle has frequently been questioned, launched his comeback as a substitute with five minutes remaining. "It is a very important day. Playing again was the most important thing to me. I have to thank everybody," said Adriano.
Reigning Copa Sudamericana champions Lanus were held to a goalless draw by Chilean side O'Higgins in Group 3. Finally, Ecuadorian giants Emelec came from behind at their home stadium in Guayaquil as they defeated Bolivian Bolivar 2-1 in Group 7.
Bolivar midfielder Juan Miguel Callejon opened the scoring with a tenth-minute strike, but Emelec's Angel Mena levelled one minute later. The decider came during the second half when Fernando Gimenez jumped highest at a corner to head in.