Diego Tardelli scored the only goal of the tie so far in at the Estadio Ciudad de Lanus to give the Argentinean side an uphill task if they are to win the competition.
Both teams are competing to win the tournament for the first time, with Tardelli's goal giving the Copa Libertadores holders an undoubted advantage ahead of Wednesday's second leg.
However, experienced defender Araujo does not feel the tie is over yet and backed his team-mates to turn things round, provided they learn from their mistakes.
"If you quietly fix the problems that we had in Brazil, we can win," he told Soy Granate Radio.
"We ended [the first leg] with a lot of anger, but now, lighter, we are psyched about going to Brazil for the win.
"We have to learn from our mistakes, correct them and not be complacent anymore."
Lanus have not played since their defeat on home soil and travel to Belo Horizonte with that reversal fresh in their minds.
Atletico meanwhile were in Serie A action at the weekend as they were held to a 1-1 draw by Bahia.
Luan's goal six minutes after the hour mark salvaged a point for the hosts, but coach Levir Cupli was far from pleased with his side's showing.
He also warned his players that they could be in for a disappointment on Wednesday if they turn in a similar performance against Lanus.
Culpi questioned after the draw: "Normally Atletico plays with fast, quick touches, but why did it only happen in the second half? I could not understand.
"Now the team is preparing for Wednesday and I'm sure that our attitude will be different from what we had in the first half [against Bahia].
"It has to be different if we want to win the title."
