[2] The draw for the first stage was held on 20 December 2017, 20:00 PYST (UTC−3), at the CONMEBOL Convention Centre in Luque, Paraguay.
If still tied, extra time would not be played, and the penalty shoot-out would be used to determine the winner (Regulations Article 27).
Tied 4–4 on aggregate, LDU Quito won on away goals and advanced to the second stage.
Tied 0–0 on aggregate, Nacional won on penalties and advanced to the second stage.
Tied 3–3 on aggregate, Sol de América won on away goals and advanced to the second stage.
Tied 2–2 on aggregate, Deportivo Cuenca won on penalties and advanced to the second stage.