# 2021 NÖ Open – Singles

This was the first edition of the tournament.
Mats Moraing won the title after defeating Hugo Gaston 6–2, 6–1 in the final.

## Seeds

* Marco Cecchinato (first round)
* Jiří Veselý (semifinals)
* Thiago Monteiro (quarterfinals)
* Kamil Majchrzak (semifinals)
* Jozef Kovalík (second round)
* Damir Džumhur (first round)
* Dennis Novak (quarterfinals)
* Hugo Gaston (final)

## 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 |
| 8 | Hugo Gaston | 6 | 3 | 6 | | | | |
| 4 | Kamil Majchrzak | 3 | 6 | 4 | | | | |
| 4 | Kamil Majchrzak | 3 | 6 | 4 | 8 | Hugo Gaston | 2 | 1 |
| | | | | | | Mats Moraing | 6 | 6 |
| | Mats Moraing | 3 | 7 | 6 | | Mats Moraing | 6 | 6 |
| 2 | Jiří Veselý | 6 | 5 | 3 | | | | |

### 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 | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals | Semifinals |
| 1 | M Cecchinato | 6$^1$ | 6 | 2 | | | | | | | | | | | | | | | |
| WC | F Misolic | 7$^7$ | 2 | 6 | WC | F Misolic | 6$^2$ | 6 | 6 | | | | | | | | | | |
| Q | M Martineau | 2 | 6$^4$ | | | J Forejtek | 7$^7$ | 3 | 2 | | | | | | | | | | |
| | J Forejtek | 6 | 7$^7$ | | | | | | | WC | F Misolic | 0 | 6 | 3 | | | | | |
| | S Ofner | 6 | 5 | 7$^7$ | | | | | | 8 | H Gaston | 6 | 2 | 6 | | | | | |
| Q | B Hassan | 3 | 7 | 6$^5$ | | S Ofner | 1 | 4 | | | | | | | | | | | |
| Q | N Oberleitner | 6$^5$ | 2 | | 8 | H Gaston | 6 | 6 | | | | | | | | | | | |
| 8 | H Gaston | 7$^7$ | 6 | | | | | | | | | | | | 8 | H Gaston | 6 | 3 | 6 |
| 4 | K Majchrzak | 3 | 6 | 6 | | | | | | | | | | | 4 | K Majchrzak | 3 | 6 | 4 |
| | H Rune | 6 | 4 | 2 | 4 | K Majchrzak | 6 | 6 | | | | | | | | | | | |
| | J Lehečka | 6 | 6 | | | J Lehečka | 1 | 0 | | | | | | | | | | | |
| | M Janvier | 4 | 3 | | | | | | | 4 | K Majchrzak | 7$^7$ | 7 | | | | | | |
| Alt | J Härteis | 6 | 4 | 3 | | | | | | | M-A Hüsler | 6$^5$ | 5 | | | | | | |
| | F Horanský | 4 | 6 | 6 | | F Horanský | 6 | 1 | 4 | | | | | | | | | | |
| | M-A Hüsler | 6$^5$ | 6 | 6 | | M-A Hüsler | 2 | 6 | 6 | | | | | | | | | | |
| 6 | D Džumhur | 7$^7$ | 2 | 3 | | | | | | | | | | | | | | | |

### 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 | Semifinals |
| 5 | J Kovalík | 6 | 3 | 7 | | | | | | | | | | | | | | | |
| | Y Hanfmann | 3 | 6 | 5 | 5 | J Kovalík | 6 | 3 | 4 | | | | | | | | | | |
| | M Moraing | 6 | 6 | | | M Moraing | 2 | 6 | 6 | | | | | | | | | | |
| Alt | L Miedler | 2 | 1 | | | | | | | | M Moraing | 6 | 0 | 7$^7$ | | | | | |
| | A Erler | 4 | 7 | 1 | | | | | | 3 | T Monteiro | 1 | 6 | 6$^5$ | | | | | |
| | L Rosol | 6 | 5 | 6 | | L Rosol | 6$^6$ | 1 | | | | | | | | | | | |
| | M Bachinger | 6 | 1 | 1 | 3 | T Monteiro | 7$^8$ | 6 | | | | | | | | | | | |
| 3 | T Monteiro | 3 | 6 | 6 | | | | | | | | | | | | M Moraing | 3 | 7 | 6 |
| 7 | D Novak | 1 | 6 | 6 | | | | | | | | | | | 2 | J Veselý | 6 | 5 | 3 |
| Q | U Ignatik | 6 | 4 | 2 | 7 | D Novak | 7 | 6 | | | | | | | | | | | |
| WC | G Melzer | 2 | 6 | 5 | | F Meligeni Alves | 5 | 4 | | | | | | | | | | | |
| | F Meligeni Alves | 6 | 3 | 7 | | | | | | 7 | D Novak | 3 | 3 | | | | | | |
| | C-M Stebe | 3 | 0 | | | | | | | 2 | J Veselý | 6 | 6 | | | | | | |
| | G Blancaneaux | 6 | 6 | | | G Blancaneaux | 1 | 1 | | | | | | | | | | | |
| WC | L Neumayer | 5 | 6$^8$ | | 2 | J Veselý | 6 | 6 | | | | | | | | | | | |
| 2 | J Veselý | 7 | 7$^{10}$ | | | | | | | | | | | | | | | | |