| UTR Pro Tennis Series Nis | 2021/10/04 10:00 | Aleksa Mardjonovic v Dusan Trunic | 6-3,6-2 |
| ITF M15 Pirot | 2021/09/21 12:25 | Aleksa Mardjonovic v Kristijan Juhas | 2-6,4-6 |
| ITF M15 Pirot | 2021/09/20 11:00 | Paul Valsecchi v Aleksa Mardjonovic | 4-6,6-4,6-10 |
| ITF M15 Pirot | 2021/09/19 12:30 | Dusan Trunic v Aleksa Mardjonovic | 4-6,6-2,7-10 |
| ITF M15 Zlatibor | 2021/09/15 13:20 | Aleksa Mardjonovic v Petar Pjevcevic | 6-1,3-6,3-6 |
| ITF M15 Ulcinj | 2021/09/05 07:30 | Aleksa Mardjonovic v Alessandro Procopio | 7-6,4-6,6-10 |
| ITF M15 Ulcinj | 2021/08/30 13:30 | Pietro Marino v Aleksa Mardjonovic | 6-4,7-6 |
| ITF M15 Ulcinj | 2021/08/30 07:30 | Aleksa Mardjonovic v Obrad Markovski | 6-7,7-5,11-9 |
| UTR Pro Tennis Series Nis | 2021/10/04 11:30 | Christos Keisidis v Alexander Lazov | 6-3,0-6,3-6 |
| UTR Pro Tennis Series Zadar | 2021/10/03 09:30 | Admir Kalender v Christos Keisidis | 6-2,6-0 |
| UTR Pro Tennis Series Zadar | 2021/10/02 11:30 | Christos Keisidis v Ivan Denisov | 3-6,6-1,6-5 |
| UTR Pro Tennis Series Zadar | 2021/10/01 08:00 | Christos Keisidis v Drazen Petrovic | 6-4,6-4 |
| UTR Pro Tennis Series Zadar | 2021/09/30 09:30 | Christos Keisidis v Stefanos Sakellaridis | 4-6,6-4,6-4 |
| UTR Pro Tennis Series Zadar | 2021/09/29 08:00 | Duje Kekez v Christos Keisidis | 6-2,2-6,5-6 |
| UTR Pro Tennis Series Zadar | 2021/09/28 12:30 | Janos Fekete v Christos Keisidis | 6-4,5-3 |
| UTR Pro Tennis Series Mulheim | 2021/09/25 10:30 | Christos Keisidis v Lawrence Bataljin | 6-4,5-3 |