In an occasionally bad-tempered group four clash, three red cards were flashed as Fluminense of Brazil beat Argentina's Arsenal 1-0.
Velez playmaker David Ramirez scored the first goal of the competition when he rifled in a shot from the edge of the box past goalkeeper Yonatan Irrazabal in the 41st minute in Montevideo.
New signing Mauro Obolo (pictured) made it 2-0 in the 81st minute when he volleyed home from close range and defender Sebastian Dominguez completed the win with a goal many of the world's top strikers would have been proud of, steering a free-kick from outside the box into the top corner with five minutes left.
Asked if it was his best ever goal, man-of-the-match Dominguez told Fox Sports: "Probably, I've scored so few."
Arsenal could have used their former striker Obolo, who was transferred to Velez last month, as their finishing was poor in the group four match in Rio de Janeiro.
Brazil striker Fred netted the only goal after two minutes and Fluminense clung on with nine men at the end.
Fluminense's Wagner and Nicolas Aguirre of Arsenal were sent off after some pushing among the players after a tackle in the 74th minute.
Fluminense defender Leandro Euzebio was also shown the red card in the final minute after he struck Arsenal's Damian Perez in the face with his heel after both went down in a tackle.
Holders Santos make their group one bow away to Bolivia's The Strongest at high altitude in La Paz next week.
Boca Juniors return to the competition for the first time since they lost to Defensor Sporting in the round of 16 in 2009 with a visit to Venezuelan newcomers Zamora in group four.
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