| 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 |
| ITF - M15 Heraklion | 2021/05/31 06:30 | Mattia Bellucci v Christos Keisidis | 6-4,6-3 |
| ITF - M15 Heraklion | 2021/05/24 06:30 | Christos Keisidis v William Griffith | 2-6,3-6 |
| ITF - M15 Heraklion | 2021/05/23 08:00 | Matic Dimic v Christos Keisidis | 2-6,4-6 |
| ITF - M15 Heraklion | 2021/05/19 06:30 | Christos Keisidis v Aristotelis Thanos | 2-6,2-6 |
| UTR Pro Tennis Series - Pazardžik | 2021/07/17 09:00 | Denislav Prodanov v Valentin Vanta | 2-6,3-6 |
| UTR Pro Tennis Series - Pazardžik | 2021/07/16 07:30 | Petyr Kardzhiev v Denislav Prodanov | 0-6,1-6 |
| UTR Pro Tennis Series - Pazardžik | 2021/07/15 10:30 | Iliyan Radulov v Denislav Prodanov | 2-6,2-6 |
| UTR Pro Tennis Series - Pazardžik | 2021/07/13 09:00 | Dian Nedev v Denislav Prodanov | 6-7,4-5 |
| UTR Pro Tennis Series - Pazardžik | 2021/07/12 07:30 | Denislav Prodanov v Ilya Snitari | 1-6,1-6 |
| ITF - M15 Sofia | 2021/07/07 07:00 | Timo Legout v Denislav Prodanov | 6-0,7-6 |
| ITF - M15 Sofia | 2021/07/05 07:00 | Denislav Prodanov v Mihnea L.S. Turcu | 6-0,6-0 |
| ITF - M15 Sofia | 2021/07/04 06:30 | Obrad Markovski v Denislav Prodanov | 1-6,7-5,7-10 |