2021 Open de Rennes

The 2021 Open de Rennes was a professional tennis tournament played on hard courts. It was the fifteenth edition of the tournament and part of the 2021 ATP Challenger Tour. It took place in Rennes, France between 13 and 19 September 2021.

Seeds

 * 1 Rankings are as of 30 August 2021.

Other entrants
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

Singles

 * 🇫🇷 Benjamin Bonzi def. 🇩🇪 Mats Moraing 7–6(7–3), 7–6(7–3).

Doubles

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