There is a clear favourite in the other semi-final - and it is not Penarol, although the Uruguayan club are one of the great names of the Libertadores. They were the first champions in 1960, and have won the title five times. The last, though, was in 1987, when young striker Diego Aguirre scored the winner in the final minute. Aguirre is now the coach, and is well aware of the size of the task ahead.
Once football's global market opened up, it became very hard for Uruguayan clubs to compete. Penarol lost the 2011 final to a Neymar-inspired Santos, but otherwise this is the first time for decades that they have gone far in the competition.
Recent Penarol sides have often been full of youth products. This one is more experienced, with the key names - such as striker Maxi Silvera and outstanding attacking midfielder Leo Fernandez - recently brought in. Former Premier League playmaker Gaston Ramirez often brings calm and quality from the bench late in games, and the mix was enough to beat Brazilian giants Flamengo in the last round.
But this one, as Aguirre recognises, will be tougher.
Current leaders of the Brazilian top flight, Botafogo combine a glorious tradition with a dismal recent past. Crippled by debt, the Rio club were becoming all too familiar with the second division until investment from US billionaire John Textor, whose Eagle Holdings also owns Lyon and has a stake in Crystal Palace.
But the rise of Botafogo is not just about money. It is also a tale of magnificent scouting, and good coaching by the Portuguese Artur Jorge, who has seamlessly introduced the new signings.
A few months ago 23-year-old centre-forward Igor Jesus was a relative unknown playing for Al-Ahli in the United Arab Emirates. This month he won his first two Brazil caps and scored his first international goal.
Also on target for Brazil this month was winger Luiz Henrique, in rich form since joining the club from Real Betis. Recent reinforcements include the Premier League full-back duo of Vitinho, formerly of Burnley, and Alex Telles, once of Manchester United, plus Argentina midfielder Thiago Almada.
How long some of these players will stay at Botafogo is an interesting question, but for the moment the club's fans are revelling in a return to the glory days of Garrincha and his illustrious team-mates of the 1950s and '60s.
Botafogo have never won the Copa Libertadores, and will be looking to put that right, starting by building a first-leg lead in front of their own fans on Thursday (01:30 BST).