# 2021 Poznań Open – Singles

Tommy Robredo was the defending champion but chose not to defend his title.
Bernabé Zapata Miralles won the title after defeating Jiří Lehečka 6–3, 6–2 in the final.

## Seeds

* Bernabé Zapata Miralles (champion)
* Botic van de Zandschulp (quarterfinals)
* Henri Laaksonen (withdrew)
* Hugo Gaston (withdrew)
* Zdeněk Kolář (quarterfinals)
* Enzo Couacaud (first round)
* Dmitry Popko (semifinals)
* Guido Andreozzi (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 |
| 1 | Bernabé Zapata Miralles | 1 | 7 | 7 | | | | |
| 7 | Dmitry Popko | 6 | 5 | 5 | | | | |
| 7 | Dmitry Popko | 6 | 5 | 5 | 1 | Bernabé Zapata Miralles | 6 | 6 |
| | | | | | | Jiří Lehečka | 3 | 2 |
| Q | A Shevchenko | 4 | 2 | | | Jiří Lehečka | 3 | 2 |
| | Jiří Lehečka | 6 | 6 | | | | | |

### 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 | B Zapata Miralles | 6 | 6 | | | | | | | | | | | | | | | | |
| | K Coppejans | 1 | 1 | | 1 | B Zapata Miralles | 4 | 7 | 6 | | | | | | | | | | |
| | M Moraing | 6 | 6 | | | M Moraing | 6 | 5 | 3 | | | | | | | | | | |
| | T Kamke | 4 | 2 | | | | | | | 1 | B Zapata Miralles | 6 | 7$^{10}$ | | | | | | |
| | F Mena | 6 | 0 | 6 | | | | | | | A Müller | 2 | 6$^8$ | | | | | | |
| | J de Jong | 3 | 6 | 4 | | F Mena | 3 | 2 | | | | | | | | | | | |
| | A Müller | 6 | 6 | | | A Müller | 6 | 6 | | | | | | | | | | | |
| 6 | E Couacaud | 3 | 2 | | | | | | | | | | | | 1 | B Zapata Miralles | 1 | 7 | 7 |
| LL | E Furness | 2 | 5 | | | | | | | | | | | | 7 | D Popko | 6 | 5 | 5 |
| SE | N Kicker | 6 | 7 | | SE | N Kicker | 6 | 6 | | | | | | | | | | | |
| WC | Aleksander Orlikowski | 3 | 5 | | | M Guinard | 2 | 4 | | | | | | | | | | | |
| | M Guinard | 6 | 7 | | | | | | | SE | N Kicker | 6 | 4 | 2 | | | | | |
| | M Janvier | 3 | 2 | | | | | | | 7 | D Popko | 3 | 6 | 6 | | | | | |
| | R Marcora | 6 | 6 | | | R Marcora | 0 | 3 | | | | | | | | | | | |
| | V Kopřiva | 4 | 6 | 5 | 7 | D Popko | 6 | 6 | | | | | | | | | | | |
| 7 | D Popko | 6 | 4 | 7 | | | | | | | | | | | | | | | |

### Bottom half

| 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 |
| 5 | Z Kolář | 6 | 6 | | | | | | | | | | | | | |
| Alt | J Forejtek | 4 | 4 | 5 | Z Kolář | 6 | 4 | 7 | | | | | | | | |
| Alt | P Cachin | 6 | 6 | Alt | P Cachin | 4 | 6 | 5 | | | | | | | | |
| Q | J Domingues | 3 | 1 | | | | | | 5 | Z Kolář | 4 | 1 | | | | |
| Q | Elmar Ejupovic | 6 | 6 | | | | | | Q | A Shevchenko | 6 | 6 | | | | |
| Q | David Poljak | 2 | 4 | Q | E Ejupovic | 6$^3$ | 6 | 6$^3$ | | | | | | | | |
| WC | Leo Borg | 5 | 2 | Q | A Shevchenko | 7$^7$ | 3 | 7$^7$ | | | | | | | | |
| Q | A Shevchenko | 7 | 6 | | | | | | | | | | Q | A Shevchenko | 4 | 2 |
| 8 | G Andreozzi | 1 | 4 | | | | | | | | | | | J Lehečka | 6 | 6 |
| | A Vukic | 6 | 6 | | A Vukic | 3 | 4 | | | | | | | | | |
| | J Lehečka | 6 | 7 | | J Lehečka | 6 | 6 | | | | | | | | | |
| | T Lamasine | 3 | 5 | | | | | | | J Lehečka | 7 | 6 | | | | |
| LL | M Zekić | 6 | 7 | | | | | | 2 | B van de Zandschulp | 5 | 3 | | | | |
| | G Elias | 2 | 5 | LL | M Zekić | 4 | 1 | | | | | | | | | |
| WC | D Michalski | 2 | 3 | 2 | B van de Zandschulp | 6 | 6 | | | | | | | | | |
| 2 | B van de Zandschulp | 6 | 6 | | | | | | | | | | | | | |