| Date: | 22–28 March |
| Edition: | 3rd |
| Surface: | Hard (Indoor) |
| Location: | Lille, France |
| Champs: |  Zizou Bergs |
| Champd: |  Benjamin Bonzi / Antoine Hoang |
| Before Year: | 2019 |
The 2021 Play In Challenger was a professional tennis tournament played on indoor hard courts. It was the third edition of the tournament which was part of the 2021 ATP Challenger Tour. It took place in Lille, France, between 22 and 28 March 2021.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
| France | Grégoire Barrère | 116 | 1 | |
| France | Benjamin Bonzi | 126 | 2 | |
| France | Arthur Rinderknech | 127 | 3 | |
| France | Antoine Hoang | 131 | 4 | |
| Oscar Otte | 153 | 5 | ||
| France | Alexandre Müller | 197 | 6 | |
| Maximilian Marterer | 209 | 7 | ||
| France | Quentin Halys | 212 | 8 |
The following players received wildcards into the singles main draw:
Arthur Cazaux Evan Furness Lilian MarmousezThe following player received entry into the singles main draw using a protected ranking:
The following player received entry into the singles main draw as an alternate:
The following players received entry from the qualifying draw:
Zizou Bergs Jurgen Briand Baptiste Crepatte Matteo MartineauThe following player received entry as a lucky loser:
See main article: 2021 Play In Challenger – Singles.
Zizou Bergs def. Grégoire Barrère 4–6, 6–1, 7–6(7–5).See main article: 2021 Play In Challenger – Doubles.
Benjamin Bonzi / Antoine Hoang def. Dan Added / Michael Geerts 6–3, 6–1.