Sao Paulo defender Maicon pleaded for forgiveness from team-mates and the club's supporters after he was sent off in the closing stages of the side's 2-0 defeat to Atletico Nacional in their Copa Libertadores semi-final first leg.
Maicon received a straight red card in the 73rd minute of the contest at the Estadio do Morumbi on Wednesday after pushing Atletico forward Miguel Borja in the back of the head.
The dismissal proved costly for the home side, with Borja going on to score a late double as Atletico sealed a two-goal advantage heading into the next week's return leg in Medellin.
Maicon - playing in his first game for Sao Paulo since his switch from Portuguese outfit Porto was made official - conceded he made a mistake and asked for forgiveness.
"Everyone knows that I messed up, and I could have doused my aggression," said the 27-year-old centre back.
"I apologise to my team-mates and the thousands of Sao-Paulinos.
"I'm lowering my head and I will work to make back the investment that the club made to sign me."
However, Maicon retains belief the referee could have handled the situation in a different manner.
"He could have given me a yellow and talked to me, to calm me down," he added.
Sao Paulo - three-time Libertadores champions - will need to score at least twice away in Colombia if they are to have any chance of making a seventh final.