# 2021 Split Open II – Singles

Blaž Rola was the defending champion but chose not to defend his title.
Kacper Żuk won the title after defeating Mathias Bourgue 6–4, 6–2 in the final.

## Seeds

* Grégoire Barrère (first round)
* Marc Polmans (first round)
* Hugo Gaston (second round)
* Mohamed Safwat (first round)
* Kimmer Coppejans (first round)
* Lorenzo Giustino (first round)
* Filip Horanský (second round)
* Steven Diez (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 |
| | Quentin Halys | 6$^8$ | 0$^r$ | | | | | |
| | Mathias Bourgue | 7$^{10}$ | 0 | | | | | |
| | Mathias Bourgue | 7$^{10}$ | 0 | | | Mathias Bourgue | 4 | 2 |
| | | | | | Q | Kacper Żuk | 6 | 6 |
| | Elias Ymer | 7$^7$ | 0 | 1 | Q | Kacper Żuk | 6 | 6 |
| Q | Kacper Żuk | 6$^5$ | 6 | 6 | | | | |

### Top half

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals |
| 1 | G Barrère | 3 | 3 | | | | | | | | | | | | | |
| SE | P Cachin | 6 | 6 | | SE | P Cachin | 2 | 6$^2$ | | | | | | | | |
| | D Masur | 3 | 2 | | | Q Halys | 6 | 7$^7$ | | | | | | | | |
| | Q Halys | 6 | 6 | | | | | | | Q Halys | 6 | 7$^7$ | | | | |
| PR | T Kokkinakis | 6 | 5 | 6 | | | | | PR | T Kokkinakis | 3 | 6$^2$ | | | | |
| WC | D Ajduković | 4 | 7 | 3 | PR | T Kokkinakis | 6 | 6 | | | | | | | | |
| PR | D Brown | 5 | 2 | | 7 | F Horanský | 1 | 2 | | | | | | | | |
| 7 | F Horanský | 7 | 6 | | | | | | | | | | | Q Halys | 6$^8$ | 0$^r$ |
| 4 | M Safwat | 6 | 2 | 4 | | | | | | | | | | M Bourgue | 7$^{10}$ | 0 |
| | M Bourgue | 3 | 6 | 6 | | M Bourgue | 6 | 6 | | | | | | | | |
| | A Bolt | 1 | 3 | | | J Domingues | 3 | 4 | | | | | | | | |
| | J Domingues | 6 | 6 | | | | | | | M Bourgue | 6 | 1 | 7 | | | |
| Q | M Bašić | 6 | 6 | | | | | | Q | M Bašić | 4 | 6 | 5 | | | |
| | D Istomin | 3 | 1 | | Q | M Bašić | 6 | 6 | | | | | | | | |
| LL | A Collarini | 6 | 6 | | LL | A Collarini | 4 | 4 | | | | | | | | |
| 6 | L Giustino | 4 | 4 | | | | | | | | | | | | | |

### 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 | Semifinals | Semifinals | Semifinals | Semifinals | Semifinals |
| 5 | K Coppejans | 3 | 4 | | | | | | | | | | | | | | | |
| WC | N Serdarušić | 6 | 6 | | WC | N Serdarušić | 6$^2$ | 7 | 3 | | | | | | | | | |
| | A Müller | 5 | 4 | | | E Ymer | 7$^7$ | 5 | 6 | | | | | | | | | |
| | E Ymer | 7 | 6 | | | | | | | | E Ymer | 6 | 6 | | | | | |
| | C İlkel | 6 | 7$^7$ | | | | | | | | C İlkel | 3 | 4 | | | | | |
| | E Couacaud | 2 | 6$^4$ | | | C İlkel | 2 | 6 | 7$^9$ | | | | | | | | | |
| Q | L Klein | 3 | 6 | 3 | 3 | H Gaston | 6 | 3 | 6$^7$ | | | | | | | | | |
| 3 | H Gaston | 6 | 3 | 6 | | | | | | | | | | | E Ymer | 7$^7$ | 0 | 1 |
| 8 | S Diez | 3 | 5 | | | | | | | | | | | Q | K Żuk | 6$^5$ | 6 | 6 |
| | M Marterer | 6 | 7 | | | M Marterer | 4 | 6$^4$ | | | | | | | | | | |
| Q | K Żuk | 6 | 7$^7$ | | Q | K Żuk | 6 | 7$^7$ | | | | | | | | | | |
| | L Rosol | 4 | 6$^4$ | | | | | | | Q | K Żuk | 6 | 6 | | | | | |
| WC | Duje Kekez | 2 | 6$^4$ | | | | | | | | A Vukic | 4 | 1 | | | | | |
| | A Vukic | 6 | 7$^7$ | | | A Vukic | 7$^7$ | 6 | | | | | | | | | | |
| Q | Z Kolář | 6 | 6 | | Q | Z Kolář | 6$^5$ | 4 | | | | | | | | | | |
| 2 | M Polmans | 2 | 2 | | | | | | | | | | | | | | | |