Copa Sudamericana wrap: Tigre, Catolica into semi-finals
The Argentinean side required a late strike from Alejandro Donatti to secure the win and their spot in the next stage along with Universidad Catolica, who also won through on Thursday.
Goals from Mariano Echeverria, Ruben Botta and Federico Santander put Tigre in the box seat early in the second half but their Paraguayan opponents were not done.
Santiago Salcedo made it 3-1 in the 62nd minute and Jonathan Fabbro put the tie back in Cerro Porteno's favour less than 10 minutes later.
But Donatti popped up for the home side just four minutes later and ensured Tigre's passage into the next round.
In the other clash, Universidad won 2-1 against Independiente thanks to a pair of penalties from Michael Rios either side of Jonathan Santana's goal for the Argentines, with all the scoring coming in the first half.
The win sent the Chilean side through 4-3 on aggregate after the first leg was locked at 2-2.
Tigre and Universidad join Sao Paulo in the last four of the competition, with the other semi-finalist to be either Colombian club Millonarios or Brazilians Gremio.