Gremio reach Libertadores last eight
The Brazilians, who face Caracas FC in the last eight, completed a 5-1 aggregate win after dominating the second round second leg tie in Porto Alegre.
Striker Jonas headed the twice former champions in front in the 18th minute from Fabio Santos's cross after a corner.
They increased their lead in the 75th minute when Maxi Lopez laid Tcheco's cross into the path of his fellow Argentine German Herrera, who rifled in the second.
San Martin pair Martin Arzuaga and Pedro Garcia were involved in a furious row shortly before the second goal and were separated by team mates as Peru's last remaining team bowed out of the competition.