Home advantage between teams from the same country in the preliminary stages will be decided by draw, while play-offs will be introduced for the last 16 round.

Under the new format, teams who finish second in their group in the Copa Sudamericana will face third-placed group finishers in the Copa Libertadores, in a similar way to the UEFA Europa League.

"The first phase of the tournament (Copa Sudamericana) will be played in single matches and the two-legged format will be abolished," CONMEBOL said in a statement.

"In addition, teams that finish second in their groups will no longer be eliminated outright, but will have the chance to advance to the Round of 16 by playing a play-off with the third-placed clubs in the Libertadores."

Chile's Universidad Catolica president Juan Tagle expressed his dissatisfaction with the modifications and issued a letter to the president of the Chilean Football Association.

"Never before has a draw established a clear sporting advantage for one of the two teams involved in a match. Who came up with this?," Tagle wrote on Twitter.

The first phase of both CONMEBOL competitions is set to be played in March, the same month the final groups will be drawn.

Flamengo are the reigning champions of the Copa Libertadores and Independiente del Valle won the last Copa Sudamericana.