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The 1970 Copa Libertadores de América was the 11th edition of CONMEBOL's top Association football club tournament. Estudiantes successfully defended their title for the second straight year by defeating Peñarol in the finals. Teams from Brazil did not participate in this year's tournament due to CBF still disagreeing with the format.
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 Argentina competed as Estudiantes were the champions of the 1969 Copa Libertadores. They entered the tournament in the semifinals.
From this phase onwards, the team that advanced from groups that had two teams (including the winner of the finals) had to decided by points (two for a win, one for a draw). If after two games, no one team had the most points, a single-game playoff was to be played on neutral grounds to determine who advanced (or wins as is the case for the finals). If the playoff game ended in a draw, goal difference will be used a tie-breaker.