# 2021 Open Quimper Bretagne – Singles

Cem İlkel was the defending champion but chose to compete in Antalya instead.
Sebastian Korda won the title after defeating Filip Horanský 6–1, 6–1 in the final.

## Seeds

* Lucas Pouille (first round)
* Sebastian Korda (champion)
* Grégoire Barrère (second round)
* Denis Kudla (first round)
* Federico Gaio (second round)
* Jurij Rodionov (first round)
* Peter Gojowczyk (first round)
* Marc-Andrea Hüsler (first round)

## Draw
### Key

* Q = Qualifier
* WC = Wild card
* LL = Lucky loser
* Alt = Alternate
* SE = Special exempt
* PR = Protected ranking
* ITF = ITF entry
* JE = Junior exempt
* w/o = Walkover
* r = Retired
* d = Defaulted
* SR = Special ranking

### Finals

| Semifinals | Semifinals | Semifinals | Semifinals | Semifinals | Final | Final | Final | Final |
| | Filip Horanský | 7$^{12}$ | 4 | 6 | | | | |
| | Brandon Nakashima | 6$^{10}$ | 6 | 4 | | | | |
| | Brandon Nakashima | 6$^{10}$ | 6 | 4 | | Filip Horanský | 1 | 1 |
| | | | | | 2 | Sebastian Korda | 6 | 6 |
| | Benjamin Bonzi | 6$^5$ | 6$^1$ | | 2 | Sebastian Korda | 6 | 6 |
| 2 | Sebastian Korda | 7$^7$ | 7$^7$ | | | | | |

### Top half

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals |
| 1 | L Pouille | 4 | 7 | 4 | | | | | | | | | | | | | |
| | F Horanský | 6 | 5 | 6 | | F Horanský | 6$^6$ | 7 | 6 | | | | | | | | |
| | M Marterer | 5 | 6 | 7$^8$ | | M Marterer | 7$^8$ | 5 | 4 | | | | | | | | |
| | S Ofner | 7 | 4 | 6$^6$ | | | | | | | F Horanský | 6 | 7 | | | | |
| Q | Antoine Cornut-Chauvinc | 5 | 6$^4$ | | | | | | | Q | K Żuk | 3 | 5 | | | | |
| | A Rinderknech | 7 | 7$^7$ | | | A Rinderknech | 6$^7$ | 2 | | | | | | | | | |
| Q | K Żuk | 6 | 6 | | Q | K Żuk | 7$^9$ | 6 | | | | | | | | | |
| 7 | P Gojowczyk | 4 | 3 | | | | | | | | | | | F Horanský | 7$^{12}$ | 4 | 6 |
| 4 | D Kudla | 2 | 6$^6$ | | | | | | | | | | | B Nakashima | 6$^{10}$ | 6 | 4 |
| WC | C Lestienne | 6 | 7$^8$ | | WC | C Lestienne | 6 | 6 | | | | | | | | | |
| | L Lacko | 3 | 7$^7$ | 6$^4$ | | D Istomin | 4 | 4 | | | | | | | | | |
| | D Istomin | 6 | 6$^2$ | 7$^7$ | | | | | | WC | C Lestienne | 4 | 5 | | | | |
| | M Janvier | 3 | 2 | | | | | | | | B Nakashima | 6 | 7 | | | | |
| | B Nakashima | 6 | 6 | | | B Nakashima | 6 | 6 | | | | | | | | | |
| | E Gulbis | 4 | 6$^3$ | | 5 | F Gaio | 2 | 1 | | | | | | | | | |
| 5 | F Gaio | 6 | 7$^7$ | | | | | | | | | | | | | | |

### Bottom half

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals |
| 8 | M-A Hüsler | 3 | 7$^7$ | 6$^5$ | | | | | | | | | | | | | | |
| | B Bonzi | 6 | 6$^2$ | 7$^7$ | | B Bonzi | 4 | 6 | 7$^7$ | | | | | | | | | |
| | T Fabbiano | 1 | 7 | 1 | | Y Maden | 6 | 2 | 6$^5$ | | | | | | | | | |
| | Y Maden | 6 | 5 | 6 | | | | | | | B Bonzi | 6$^7$ | 6 | 6 | | | | |
| WC | A Cazaux | 4 | 5 | | | | | | | Q | I Marchenko | 7$^9$ | 4 | 4 | | | | |
| Q | I Marchenko | 6 | 7 | | Q | I Marchenko | 6 | 6 | | | | | | | | | | |
| | H Gaston | 3 | 4 | | 3 | G Barrère | 3 | 2 | | | | | | | | | | |
| 3 | G Barrère | 6 | 6 | | | | | | | | | | | | | B Bonzi | 6$^5$ | 6$^1$ |
| 6 | J Rodionov | 3 | 6 | 4 | | | | | | | | | | | 2 | S Korda | 7$^7$ | 7$^7$ |
| | E Couacaud | 6 | 1 | 6 | | E Couacaud | 6 | 6$^5$ | 6 | | | | | | | | | |
| WC | E Furness | 6 | 6 | | WC | E Furness | 4 | 7$^7$ | 3 | | | | | | | | | |
| | R Marcora | 2 | 1 | | | | | | | | E Couacaud | 1$^r$ | | | | | | |
| | M Bourgue | 7$^7$ | 6 | | | | | | | 2 | S Korda | 4 | | | | | | |
| | L Rosol | 6$^5$ | 4 | | | M Bourgue | 7 | 6$^2$ | 4 | | | | | | | | | |
| Q | T Lamasine | 6$^3$ | 6 | 6$^7$ | 2 | S Korda | 5 | 7$^7$ | 6 | | | | | | | | | |
| 2 | S Korda | 7$^7$ | 4 | 7$^9$ | | | | | | | | | | | | | | |