2021 Open de Rennes

Country	Player	Rank1	Seed
FRA	Richard Gasquet	79	1
FRA	Arthur Rinderknech	83	2
FRA	Benjamin Bonzi	94	3
FRA	Gilles Simon	103	4
GBR	Andy Murray	112	5
FRA	Lucas Pouille	133	6
FRA	Grégoire Barrère	136	7
CZE	Tomáš Macháč	143	8

• ¹ Rankings are as of 30 August 2021.^[1]

The following players received wildcards into the singles main draw:

• Kyrian Jacquet
• Harold Mayot
• Andy Murray

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

• Teymuraz Gabashvili

The following players received entry from the qualifying draw:

• Alessandro Bega
• Clément Chidekh
• Manuel Guinard
• Calvin Hemery

The following players received entry as lucky losers:

• Dan Added
• Mats Rosenkranz

• Benjamin Bonzi def. Mats Moraing 7–6^(7–3), 7–6^(7–3).

• Bart Stevens / Tim van Rijthoven def. Marek Gengel / Tomáš Macháč 6–7^(2–7), 7–5, [10–3].