first international title - erase the 2-0 deficit established by Olimpia in Paraguay last week.
"We still believe," Ronaldinho wrote on Twitter. "It's not over yet. We have one game to go and we will give our blood to win this title. We believe in the strength of this group and in the strength of the fans."
The Copa Libertadores is one of the few titles Ronaldinho hasn't won in his career. After a decade in Europe with Paris Saint-Germain, Barcelona and Milan, he returned to Brazilian glamor club Flamengo in 2011 before an abrupt departure to Atletico Mineiro last year.
"This title means more than anything else for us," the 33-year-old Ronaldinho said.
His move to the Belo Horizonte club quickly vaulted it to being a top contender in Brazil and Latin America, and his teammates are hoping the former Brazil star will lead them to the coveted title on Wednesday.
"The team improved significantly after Ronaldinho arrived and we all have a lot of trust in him in a decisive moment like this," striker Jo said.
Forward Diego Tardelli added: "We know he is the star of our team and everybody respects him a lot for that."
It was a difficult first-leg loss for Ronaldinho and Atletico, with Olimpia's second goal coming on a free kick in the final play of the match. Ronaldinho was far from his best, being ineffective through most of the game and being replaced in the second half.
But there is reason for the Brazilian club to remain optimistic despite the loss.
Atletico Mineiro was in the same situation in the semifinals after losing 2-0 to Newell's Old Boys in the first leg in Argentina. Ronaldinho was great in the return game at home, though, and Atletico Mineiro won the match by the same score and eventually came out on top in a shootout, with goalkeeper Victor making a save in the last penalty.
Victor also saved an injury-time penalty against Tijuana of Mexico in the quarterfinals.
Olimpia has already relinquished a two-goal first leg lead in the final of the Copa Libertadores. It happened in 1989, when it fell to Atletico Nacional of Colombia on penalties, marking the last time such advantage was lost.
Olimpia won the tournament the following year, adding to the trophy it had won for the first time in 1979.
The Paraguayans made it to this year's final by holding on to that same two-goal advantage against Colombia's Santa Fe. It won 2-0 at home and advanced despite a 1-0 loss in the away leg.
Olimpia is hoping to repeat the success of the last time it played a final against a Brazilian club, in 2002. It lost 1-0 to Sao Caetano in the first leg at home but won the return in Brazil 2-1 and clinched the title on penalties.
This is the ninth straight year that at least one Brazilian team has made the final. Brazilian clubs have won the past three titles: Corinthians last year, Santos in 2011 and Internacional in 2010.
The newly renovated Mineirao Stadium, which holds about 60,000 fans, is expected to be packed in Wednesday's match.
Atletico wanted to play the final at its Independencia Stadium, where it hasn't lost in nearly 40 matches, but the South American football federation (CONMEBOL) deemed the venue too small for the final of the continental tournament. It holds just over 20,000 fans.
Atletico Mineiro is traditionally one of the power clubs in Brazil but has not had a lot of success internationally. It won the CONMEBOL Cup in 1992 and 1997.
IFor Wednesday's match, coach Alexi Stival "Cuca" will have the return of young Brazil striker Bernard, who was suspended for the first leg.