2021 Challenger de Santiago III

Country	Player	Rank1	Seed
ARG	Juan Manuel Cerúndolo	103	1
ARG	Francisco Cerúndolo	110	2
PER	Juan Pablo Varillas	127	3
BRA	Thiago Seyboth Wild	129	4
ARG	Sebastián Báez	140	5
CHI	Marcelo Tomás Barrios Vera	154	6
ARG	Juan Ignacio Londero	157	7
FRA	Enzo Couacaud	189	8

• ¹ Rankings are as of 4 October 2021.^[1]

The following players received wildcards into the singles main draw:

• Diego Fernández Flores
• Matías Soto
• Benjamín Torres

The following player received entry into the singles main draw using a protected ranking:

• Gerald Melzer

The following players received entry into the singles main draw as alternates:

• Hernán Casanova
• Nick Chappell
• Facundo Díaz Acosta
• Gonzalo Lama

The following players received entry from the qualifying draw:

• Nicolás Álvarez
• Oliver Crawford
• Diego Hidalgo
• Rafael Matos

The following player received entry as a lucky loser:

• Lucas Catarina

• Sebastián Báez def. Felipe Meligeni Alves 3–6, 7–6^(8–6), 6–1.

• Evan King / Max Schnur def. Hans Hach Verdugo / Miguel Ángel Reyes-Varela 3–6, 7–6^(7–3), [16–14].