# 2023 Ostra Group Open – Singles

Evan Furness was the defending champion but retired from his first round match against Gaël Monfils.
Zdeněk Kolář won the title after defeating Máté Valkusz 6–3, 6–2 in the final.

## Seeds

* Ryan Peniston (first round)
* Ivan Gakhov (second round)
* Vít Kopřiva (second round)
* Geoffrey Blancaneaux (second round)
* Alejandro Tabilo (withdrew)
* Riccardo Bonadio (semifinals)
* Oleksii Krutykh (second round)
* Damir Džumhur (quarterfinals)
* Dalibor Svrčina (second 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 |
| Alt | Shintaro Mochizuki | 3 | 6 | 2 | | | |
| | Zdeněk Kolář | 6 | 2 | 6 | | | |
| | Zdeněk Kolář | 6 | 2 | 6 | Zdeněk Kolář | 6 | 6 |
| | | | | | Máté Valkusz | 3 | 2 |
| | Máté Valkusz | 6 | 6 | | Máté Valkusz | 3 | 2 |
| 6 | Riccardo Bonadio | 0 | 4 | | | | |

### 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 | R Peniston | 2 | 3 | | | | | | | | | | | | | | | | |
| WC | J Menšík | 6 | 6 | | WC | J Menšík | 6 | 2 | 6$^4$ | | | | | | | | | | |
| Q | G Andreozzi | 6 | 4 | 1 | Alt | S Mochizuki | 1 | 6 | 7$^7$ | | | | | | | | | | |
| Alt | S Mochizuki | 2 | 6 | 6 | | | | | | Alt | S Mochizuki | 5 | 6 | 6 | | | | | |
| WC | G Monfils | 6 | 2 | | | | | | | 8 | D Džumhur | 7 | 2 | 3 | | | | | |
| | E Furness | 3 | 0$^r$ | | WC | G Monfils | 3 | 4 | | | | | | | | | | | |
| Q | H Squire | 3 | 0 | | 8 | D Džumhur | 6 | 6 | | | | | | | | | | | |
| 8 | D Džumhur | 6 | 6 | | | | | | | | | | | | Alt | S Mochizuki | 3 | 6 | 2 |
| 3 | V Kopřiva | 7 | 4 | 6 | | | | | | | | | | | | Z Kolář | 6 | 2 | 6 |
| | D Added | 5 | 6 | 3 | 3 | V Kopřiva | 2 | 1 | | | | | | | | | | | |
| | M Zekić | 6$^9$ | 2 | | | Z Kolář | 6 | 6 | | | | | | | | | | | |
| | Z Kolář | 7$^{11}$ | 6 | | | | | | | | Z Kolář | 6 | 2 | 6 | | | | | |
| | G Onclin | 4 | 6 | 6 | | | | | | | G Onclin | 2 | 6 | 4 | | | | | |
| Alt | V Sachko | 6 | 4 | 2 | | G Onclin | 6 | 6 | | | | | | | | | | | |
| Q | R Molleker | 0 | 6 | 1 | 9 | D Svrčina | 0 | 3 | | | | | | | | | | | |
| 9 | D Svrčina | 6 | 2 | 6 | | | | | | | | | | | | | | | |

### 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 |
| 7 | O Krutykh | 6 | 6 | | | | | | | | | | | | | | | |
| | ND Ionel | 1 | 2 | | 7 | O Krutykh | 1 | 4 | | | | | | | | | | |
| | R Collignon | 4 | 4 | | | F Ferreira Silva | 6 | 6 | | | | | | | | | | |
| | F Ferreira Silva | 6 | 6 | | | | | | | | F Ferreira Silva | 6$^4$ | 1 | | | | | |
| Q | P Rikl | 3 | 6 | 1 | | | | | | | M Valkusz | 7$^7$ | 6 | | | | | |
| | M Valkusz | 6 | 4 | 6 | | M Valkusz | 6 | 6 | | | | | | | | | | |
| | Pol Martín Tiffon | 4 | 3 | | 4 | G Blancaneaux | 3 | 4 | | | | | | | | | | |
| 4 | G Blancaneaux | 6 | 6 | | | | | | | | | | | | | M Valkusz | 6 | 6 |
| 6 | R Bonadio | 6 | 6 | | | | | | | | | | | | 6 | R Bonadio | 0 | 4 |
| Q | Àlex Martí Pujolràs | 4 | 3 | | 6 | R Bonadio | 6 | 7$^7$ | | | | | | | | | | |
| Q | K Sultanov | 2 | 0 | | | H Mayot | 1 | 6$^3$ | | | | | | | | | | |
| | H Mayot | 6 | 6 | | | | | | | 6 | R Bonadio | 6$^5$ | 6 | 6 | | | | |
| WC | J Veselý | 6 | 6$^7$ | 6 | | | | | | WC | J Veselý | 7$^7$ | 3 | 4 | | | | |
| | L Giustino | 3 | 7$^9$ | 2 | WC | J Veselý | 2 | 6 | 6 | | | | | | | | | |
| | L Rosol | 4 | 6 | 1 | 2 | I Gakhov | 6 | 3 | 4 | | | | | | | | | |
| 2 | I Gakhov | 6 | 3 | 6 | | | | | | | | | | | | | | |