2021 San Marino Open

Country	Player	Rank1	Seed
ITA	Marco Cecchinato	84	1
FRA	Gilles Simon	102	2
ITA	Salvatore Caruso	111	3
BOL	Hugo Dellien	139	4
ITA	Federico Gaio	147	5
ARG	Tomás Martín Etcheverry	148	6
ARG	Sebastián Báez	156	7
SLO	Blaž Rola	173	8

• ¹ Rankings are as of 2 August 2021.^[1]

The following players received wildcards into the singles main draw:

• Raúl Brancaccio
• Marco De Rossi
• Luca Nardi

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

• Julien Cagnina

The following player received entry into the singles main draw as an alternate:

• Malek Jaziri

The following players received entry from the qualifying draw:

• Francesco Forti
• Orlando Luz
• Manuel Mazza
• Julian Ocleppo

The following player received entry as a lucky loser:

• Pavel Kotov

• Holger Rune def. Orlando Luz 1–6, 6–2, 6–3.

• Zdeněk Kolář / Luis David Martínez def. Rafael Matos / João Menezes 1–6, 6–3, [10–3].