Round: 26 Ground: Hardcourt outdoor
| ITF - Sozopol M15 | 2021/10/05 13:30 | Sarp Agabigun v Gabriel Donev | 5-7,5-7 |
| ITF - Sozopol M15 | 2021/09/15 08:30 | George Lazarov v Gabriel Donev | 6-1,6-3 |
| ITF - Ulcinj M15 | 2021/09/10 09:00 | Gabriel Donev v Edoardo Lavagno | 1-6,2-6 |
| ITF - Ulcinj M15 | 2021/09/09 09:50 | Aziz Kijametovic v Gabriel Donev | 5-7,6-7 |
| ITF - Ulcinj M15 | 2021/09/08 08:00 | Gabriel Donev v Dusan Rajic | 6-4,6-7,7-5 |
| ITF - Ulcinj M15 | 2021/09/03 08:55 | Gabriel Donev v Ignacio Carou | 4-6,3-6 |
| ITF - Ulcinj M15 | 2021/09/02 08:30 | Gorazd Srbljak v Gabriel Donev | 1-6,6-7 |
| ITF - Telavi M15 | 2021/08/04 08:45 | Evgeny Philippov v Gabriel Donev | 2-6,3-6 |
| ITF - Sozopol M15 | 2021/10/08 08:35 | Tim Handel v Alexander Donski | 3-6,6-3,2-6 |
| ITF - Sozopol M15 | 2021/10/05 15:15 | Dragos Constantin Ignat v Alexander Donski | 1-6,2-6 |
| ATP Sofia | 2021/09/27 09:00 | Andreas Seppi v Alexander Donski | 6-3,6-2 |
| ATP Sofia | 2021/09/26 09:00 | Alexander Donski v Jurij Rodionov | 2-6,6-1,7-6 |
| ITF - Plaisir M25 | 2021/09/16 09:55 | Robin Bertrand v Alexander Donski | 3-6,3-6 |
| ITF - Plaisir M25 | 2021/09/14 08:00 | Alexander Donski v Quentin Robert | 7-5,1-6,6-2 |
| ITF - Ricany M25 | 2021/09/02 08:00 | Alexander Donski v Ryan Peniston | 2-6,4-6 |
| ITF - Ricany M25 | 2021/09/01 07:55 | Daniel Paty v Alexander Donski | 3-6,3-6 |