Boca Juniors secured a narrow advantage in the first leg of their Copa Libertadores last-16 tie with Corinthians as they won 1-0 in Buenos Aires.
Nicolas Blandi got the only goal in the 59th minute but Boca were left to finish the match with ten men as substitute Pablo Ledesma was sent off with six minutes to go.
Ledesma collected two yellow cards just seconds apart, the first a caution for celebrating what proved to be a disallowed goal and then a second two minutes later for a crude challenge on Teles Ralf.
Gremio beat Colombian side Independiente Sante Fe 2-1 despite playing with ten men for the last 37 minutes.
Cris saw red for the challenge but the visitors could not capitalise on their man advantage and Fernando grabbed the winner with a low drive.