Boca looks to overturn deficit vs River in Copa semis
River is unbeaten in away games in the knockout stages since 2017 and the defending champion has only conceded one goal away from home in this year's playoffs.
Even Diego Maradona — Boca's most famous fan — has said "it is not possible" for his team to advance.
But Boca coach Gustavo Alfaro isn't paying attention to statistics or nay-sayers.
"Don't think we are dead," Alfaro said. "Tuesday's match will be the most important of my life, that is how I am living it and how I will face it."
In the other semifinal, Flamengo hosts Gremio in Rio de Janeiro's Maracana stadium on Wednesday after the teams drew 1-1 in the first leg.
Flamengo holds a 10-point lead in the Brazilian championship and enters the second leg as the favorite, despite giving up a late equalizer in the first game. The Rio-based team had dominated most of that game, and easily could have built a bigger lead in the first 45 minutes.
Flamengo, Brazil's most popular club, hasn't played in the Copa Libertadores final since 1981 when legend Zico was still active. Flamengo's Portuguese coach Jorge Jesus knows how excited fans are about a possible return, but asked for calm ahead of the decisive match against the 2017 Copa Libertadores winners.
"Soccer is cruel and there could be surprises," Jesus said after Flamengo's 2-0 win against archrivals Fluminense on Sunday. "On Wednesday it will be much more difficult."
River is looking for its fifth Copa Libertadores title, while Boca has six. Flamengo seeks its second title, while Gremio has won three.
The final is on Nov. 23 in Santiago, Chile.