Stadium: Court 1 Round: 25 Ground: Hardcourt outdoor
| ITF M15 Sozopol | 2021/09/14 07:00 | George Lazarov v Mikhail Minakov | 7-5,4-6,10-4 |
| ITF M15 Sozopol | 2021/09/13 08:00 | Luigi Castelletti v George Lazarov | 3-6,4-6 |
| UTR Pro Tennis Series Sofia | 2021/09/04 07:30 | Alexander Lazov v George Lazarov | 3-5 |
| UTR Pro Tennis Series Sofia | 2021/09/03 07:00 | George Lazarov v Christos Keisidis | 6-4,6-4 |
| UTR Pro Tennis Series Sofia | 2021/09/02 07:00 | Ivan Mikhaylyuk v George Lazarov | 3-6,1-6 |
| UTR Pro Tennis Series Sofia | 2021/09/01 06:30 | Volodymyr Uzhylovskyi v George Lazarov | 1-6,6-1,1-5 |
| UTR Pro Tennis Series Sofia | 2021/08/31 09:30 | Valentin Vanta v George Lazarov | 6-4,6-0 |
| UTR Pro Tennis Series Sofia | 2021/08/30 12:00 | Warren Sinius v George Lazarov | 2-6,2-5 |
| ITF M15 Ulcinj | 2021/09/10 09:00 | Gabriel Donev v Edoardo Lavagno | 1-6,2-6 |
| ITF M15 Ulcinj | 2021/09/09 09:50 | Aziz Kijametovic v Gabriel Donev | 5-7,6-7 |
| ITF M15 Ulcinj | 2021/09/08 08:00 | Gabriel Donev v Dusan Rajic | 6-4,6-7,7-5 |
| ITF M15 Ulcinj | 2021/09/03 08:55 | Gabriel Donev v Ignacio Carou | 4-6,3-6 |
| ITF M15 Ulcinj | 2021/09/02 08:30 | Gorazd Srbljak v Gabriel Donev | 1-6,6-7 |
| ITF M15 Telavi | 2021/08/04 08:45 | Evgeny Philippov v Gabriel Donev | 2-6,3-6 |
| ITF M15 Telavi | 2021/08/03 09:45 | Martin Borisiouk v Gabriel Donev | 3-6,2-6 |
| ITF M15 Novi Sad | 2021/07/30 08:00 | Gabriel Donev v Juan Pablo Paz | 4-6,5-7 |