The 2018 Copa Sudamericana second stage was played from 17 July to 16 August 2018. A total of 32 teams competed in the second stage to decide the 16 places in the final stages of the 2018 Copa Sudamericana.
<section begin=Draw /> The draw for the second stage was held on 4 June 2018, 20:00 PYT (), at the CONMEBOL Convention Centre in Luque, Paraguay. For the second stage, the teams were allocated to two pots according to their previous results in this season:
The 32 teams were drawn into 16 ties (O1âÂÂO16) between a team from Pot 1 and a team from Pot 2, with the teams from Pot 1 hosting the second leg. Teams from the same association could be drawn into the same tie.<section end=Draw />
The following were the 10 teams transferred from the Copa Libertadores (two best teams eliminated in the third stage of qualifying and eight third-placed teams in the group stage).
The following were the 22 winners of the first stage from the Copa Sudamericana. Matches in the first stage were considered for the ranking of teams for the second stage draw.
<section begin=Format /> In the second stage, each tie was played on a home-and-away two-legged basis. If tied on aggregate, the away goals rule would be used. If still tied, extra time would not be played, and the penalty shoot-out would be used to determine the winner (Regulations Article 27).
The 16 winners of the second stage advanced to the round of 16 of the knockout stages.<section end=Format />
The first legs were played on 17âÂÂ19, 25âÂÂ26 July, and 1âÂÂ2 August, and the second legs were played on 24, 31 July, 1âÂÂ2, 7âÂÂ9 and 14âÂÂ16 August 2018. <section begin=Second stage />
<section end=Second stage />
Millonarios won 5âÂÂ1 on aggregate and advanced to the round of 16 (Match A).
Botafogo won 3âÂÂ2 on aggregate and advanced to the round of 16 (Match B).
Nacional won 1âÂÂ0 on aggregate and advanced to the round of 16 (Match C).
Tied 1âÂÂ1 on aggregate, Colón won on penalties and advanced to the round of 16 (Match D).
Banfield won 2âÂÂ1 on aggregate and advanced to the round of 16 (Match E).
Fluminense won 3âÂÂ0 on aggregate and advanced to the round of 16 (Match F).
Atlético Paranaense won 6âÂÂ1 on aggregate and advanced to the round of 16 (Match G).
Deportivo Cali won 6âÂÂ1 on aggregate and advanced to the round of 16 (Match H).
LDU Quito won 3âÂÂ2 on aggregate and advanced to the round of 16 (Match H).
Caracas won 6âÂÂ3 on aggregate and advanced to the round of 16 (Match G).
Tied 4âÂÂ4 on aggregate, Deportivo Cuenca won on penalties and advanced to the round of 16 (Match F).
Defensa y Justicia won 2âÂÂ1 on aggregate and advanced to the round of 16 (Match E).
Tied 1âÂÂ1 on aggregate, Junior won on penalties and advanced to the round of 16 (Match D).
San Lorenzo won 3âÂÂ1 on aggregate and advanced to the round of 16 (Match C).
Bahia won 3âÂÂ1 on aggregate and advanced to the round of 16 (Match B).
Santa Fe won 2âÂÂ0 on aggregate and advanced to the round of 16 (Match A).