Corinthians lost 2-0 at Colombia's Deportes Tolima in the second leg after the first leg ended 0-0 and missed out on the group phase of South America's flagship club competition which they have never won.
"This is a defeat we're going to have to carry for the rest of the year," former FIFA World Player of the Year Ronaldo told reporters after mediocre performances in both legs against the Colombian team.
Substitute Danny Santoya put Tolima ahead after 65 minutes and Corinthians' task became even tougher when their Peruvian substitute Luis Ramirez was sent off in the 72nd for elbowing an opponent less than two minutes after coming on.
Striker Wilder Medina headed a second goal in the 77th to make sure of Tolima's passage into Group Seven where they meet four-times champions Estudiantes of Argentina, twice winners Cruzeiro of Brazil and Paraguay's Guarani.
"We can't ask for patience or tolerance from our fans. We failed and we're very sad," said Ronaldo, visibly disappointed with the result in the last season of his career.
"We didn't play well. The pitch also didn't help our team. It's inadmissible that the Conmebol (South American Confederation) accept such a field. But that isn't an excuse, our team really weren't good in either leg."
Brazil's Gremio, South American champions in 1983 and 1995, went through after a 3-1 home win over Liverpool of Uruguay in which midfielder Vinicius Pacheco scored twice to give them a 5-3 aggregate victory.
Record seven-times champions Independiente of Argentina, playing in the competition for the first time since 2004, lost 1-0 away to Deportivo Quito on Tuesday but progressed 2-1 on aggregate.
Mexico's Chiapas reached the group phase with a 4-0 aggregate win over Alianza Lima of Peru on Tuesday. Among their opponents in Group Six are holders Internacional of Brazil.
