| 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 |
| UTR Pro Tennis Series Sofia | 2021/08/29 12:00 | George Lazarov v Mario Radev | 6-0,6-1 |
| UTR Pro Tennis Series Sofia | 2021/09/02 07:00 | Vladimir Popov v Christos Keisidis | 7-6,6-7,3-6 |
| UTR Pro Tennis Series Sofia | 2021/09/01 08:00 | Christos Keisidis v Mario Radev | 6-1,4-6,6-4 |
| UTR Pro Tennis Series Sofia | 2021/08/31 08:00 | Christos Keisidis v Josh Sheehy | 4-6,4-6 |
| UTR Pro Tennis Series Sofia | 2021/08/30 07:00 | Christos Keisidis v Denislav Prodanov | 6-1,5-1 |
| ITF M15 Heraklion | 2021/06/09 08:00 | Antonio Cayetano March v Christos Keisidis | 4-6,7-6,6-2 |
| ITF M15 Heraklion | 2021/06/08 06:30 | Sean Hodkin v Christos Keisidis | 6-4,5-7,4-10 |
| ITF M15 Heraklion | 2021/06/07 09:00 | Christos Keisidis v Alexander Gaponenko | 6-4,6-1 |
| ITF M15 Heraklion | 2021/06/06 11:00 | Michel-Alexandre Fortin v Christos Keisidis | 0-6,0-6 |