The1991 Copa Libertadores was won byColo-Colo ofChile after defeatingOlimpia ofParaguay with a 3–0 aggregate score in the finals. The championship would mark a first for a Chilean club team in an international tournament. Twenty-one clubs from all South American countries withinConfederación Sudamericana de Fútbol (CONMEBOL) participated.
The champions and runners-up of each football association were drawn into the same group along with another football association's participating teams. Three clubs from Paraguay competed asOlimpia was champion of the1990 Copa Libertadores. They entered the tournament in the Second round.