Nine-man Cruzeiro draw with Deportivo Quito
Universidad de Chile pulled off an extraordinary survival act as they drew 0-0 away to Brazil's Gremio, who missed at least half a dozen clear-cut chances in Porto Alegre.
Venezuela's Caracas FC completed a dramatic night with a shock 3-1 win over Argentina's Lanus.
Deportivo Quito players last week went on strike over unpaid wages and bonuses less than two months after winning the Ecuadorean championship for the first time in 40 years.
The players resumed training on Monday for the Libertadores tie but warned they would go back on strike if they were not paid by Friday.
Ramires headed Cruzeiro ahead following a free kick in the 38th minute of the Group Five game in Quito.
The visitors had Wellington Paulista sent off four minutes later and were reduced to nine men when Fabricio followed midway through the second half.
Deportivo, who had Luis Checa dismissed in the 52nd minute, pressed forward and Bagner Caicedo headed their equaliser in injury-time.
Former champions Gremio dominated their Group Seven match but could not find a way past Universidad de Chile goalkeeper Miguel Pinto.
Pinto saved a Jonas header and Tcheco shot early on before Souza hit the post just before halftime.
Rafael Marques headed wide from a free position after the break before the game's most astonishing sequence in which Gremio missed four chances in 15 seconds.
One header was cleared off the line, another shot was blocked, another effort hit the post and the rebound was smothered by Pinto.
Alex Mineiro had a shot cleared off the line after rounding Pinto and Gremio also had a penalty appeal turned down. The visitors had Marcelo Diaz sent off for a second bookable offence in the 72nd minute.
Caracas took control of their Group Six match against Lanus by scoring twice in the first five minutes of the second half through Jose Manuel Rey, from a rocketing free kick, and Dario Figueroa.
Rafael Castellin added a third before Jose Sand pulled one back for shell-shocked Lanus. The Venezuelans collected their first points in the group while Lanus have one. Both teams have played twice.