The Paraguayan champions have not lost an encounter at Estadio Tigo La Huerta in this year's tournament, defeating Furacao 1-0 at home in the group stage.
Match preview
It is now or never for Libertad, who seem like the only team from Paraguay with a realistic shot to advance beyond this point, with Cerro Porteno trailing Palmeiras 3-0 in their Round of 16 clash.
Being a goal behind, in theory, is by no means an insurmountable deficit, however, history is not on the side of the champions from Paraguay, as it has been over a decade since Repollero advanced beyond this round when facing a deficit from their opening game, defeating Fluminense 3-0 after losing the opening fixture 3-1 in 2011.
The good news for Daniel Garnero is that his players have looked razor-sharp at home throughout the campaign, winning all three of their group stage fixtures played in Asuncion, outscoring their opponents by a margin of 7-2.
As a whole, Libertad are a difficult team to break down, playing their positions effectively and rarely suffering a lapse in concentration or discipline.
In their 13 previous home games against Brazilian sides at this tournament, Libertad have managed to earn a positive result nine times.
They have only conceded one second-half tally in their last eight matches played in all competitions, while scoring eight times themselves in the final 45 minutes.
On Saturday, the reigning Copa Sudamericana champions sent a clear message to all the teams in the Brasileiro Serie A that they are not going away, as they shocked the league leaders Palmeiras 2-0, moving within two points of first in the table.
They have been business-like in their approach since bringing legendary coach Luiz Felipe Scolari into the fold, suffering only one defeat under the 2002 World Cup-winning boss.
Furacao thrive off other teams' mistakes, with quick counter-attacking, and an ability to squeak through the smallest of gaps to score.
El Paranaense are comfortable allowing their opponents the ball for long stretches, rarely having more than 40% possession over a 90-minute encounter.
Domestically their defensive shape has been as solid as almost any side in the Brazilian top-flight, conceding the third-fewest goals in Serie A (15), though six of their seven goals allowed in the group stage of this competition were on the road.
Perhaps one of the few things working against them heading into this pivotal encounter on Tuesday is history, as Athletico have not scored a goal in the second leg of a Round of 16 clash since 2005, which was also the last time they made it beyond that point of the tournament.
Club Libertad Copa Libertadores form:
Club Libertad form (all competitions):
Athletico Paranaense Copa Libertadores form:
Athletico Paranaense form (all competitions):
Team News
Lorenzo Melgarejo is tied with his Libertad teammate William Mendieta for goals at this tournament, having each tallied twice, while Hector Villalba found the back of the net in the opening match against Athletico.
Julio Enciso leads them with 11 goals in the Paraguayan Primera Division this season, though neither he nor their number two goalscorer domestically, Roque Santa Cruz have found the back of the net in this year's showcase event.
Goalkeeper Martin Silva has played well in between the stick, as he has not conceded a goal in his last two domestic home fixtures.
Some solid work from defenders Camilo Mayada, Diego Viera, Alexander Barboza and Miguel Samudio helped them preserve a shutout in their previous home fixture versus Furacao, allowing only one shot on target in that group fixture, winning 1-0 thanks for a goal from Cristian Riveros.
Vitor Roque and Vitor Bueno tallied the only goals in the 2-0 triumph for Athletico over Palestra this past weekend, with Bento collecting a clean sheet.
Roque and Nicolas Hernandez scored in their 2-1 victory last week versus Libertad, as David Terans, and Tomas Cuello picked up assists.
Their top goalscorer in this competition, Pablo could be out of this contest as he and Vitinho have sore thighs, Marlos is nursing a calf strain and Thiago Heleno continues to deal with a shoulder injury.
Club Libertad possible starting lineup:
Silva; Samudio, Barboza, Viera, Piris; Merlini, Campuzano, Franco; Melgarejo, Santa Cruz, Villalba
Athletico Paranaense possible starting lineup:
Bento; Abner, Henrique, Felipe, Khellven; Christian, Moura; Rocha, Terans, Cuello; Roque
We say: Club Libertad 2-1 Athletico Paranaense (Atheltico Paranaense win on penalties)
There are plenty of valid reasons that might suggest each of these sides have an equal chance of capturing this encounter, making it an extremely a tough match to call.