The 2021 Copa Sudamericana first stage was played from 16 March to 14 April 2021. A total of 32 teams competed in the first stage to decide 16 of the 32 places in the group stage of the 2021 Copa Sudamericana.
<section begin=Draw /> The draw for the first stage was held on 5 February 2021, 12:00 PYST (), at the CONMEBOL Convention Centre in Luque, Paraguay. For the first stage, the 32 teams involved were divided into eight pots according to their national association.
The 32 teams were drawn into 16 ties, with the four teams from each national association drawn against each other into two ties per association (e.g., the four teams from Bolivia were drawn into ties BOL 1 and BOL 2), and the first team drawn in each tie hosting the second leg.<section end=Draw />
<section begin=Format /> In the first stage, each tie was played on a home-and-away two-legged basis. If tied on aggregate, the away goals rule was used. If still tied, extra time will not be played, and a penalty shoot-out would be used to determine the winner (Regulations Article 2.4.2).
The 16 winners of the first stage advanced to the group stage to join the 12 teams directly qualified for that stage (six from Argentina and six from Brazil), and four teams transferred from the Copa Libertadores (the four teams eliminated in the third stage of qualifying).<section end=Format />
The first legs were played on 16âÂÂ18 March, 6 and 7 April while the second legs were played on 6âÂÂ8, 13 and 14 April 2021. <section begin=First stage />
<section end=First stage />
Guabirá won 6âÂÂ2 on aggregate and advanced to the group stage (BOL 1).
Jorge Wilstermann won 4âÂÂ2 on aggregate and advanced to the group stage (BOL 2).
Huachipato won 4âÂÂ0 on aggregate and advanced to the group stage (CHI 1).
Palestino won 2âÂÂ1 on aggregate and advanced to the group stage (CHI 2).
Deportes Tolima won 3âÂÂ0 on aggregate and advanced to the group stage (COL 1).
La Equidad won 3âÂÂ2 on aggregate and advanced to the group stage (COL 2).
Emelec won 4âÂÂ2 on aggregate and advanced to the group stage (ECU 1).
Aucas won 5âÂÂ1 on aggregate and advanced to the group stage (ECU 2).
Tied 0âÂÂ0 on aggregate, 12 de Octubre won on penalties and advanced to the group stage (PAR 1).
River Plate won 6âÂÂ3 on aggregate and advanced to the group stage (PAR 2).
Sport Huancayo won 5âÂÂ0 on aggregate and advanced to the group stage (PER 1).
Melgar won 5âÂÂ3 on aggregate and advanced to the group stage (PER 2).
Montevideo City Torque won 2âÂÂ0 on aggregate and advanced to the group stage (URU 1).
Peñarol won 6âÂÂ3 on aggregate and advanced to the group stage (URU 2).
Metropolitanos won 3âÂÂ0 on aggregate and advanced to the group stage (VEN 1).
Tied 2âÂÂ2 on aggregate, Aragua won on away goals and advanced to the group stage (VEN 2).