| ITF M15 Bad Waltersdorf | 2021/08/31 07:00 | Luigi Sorrentino v Stefanos Sakellaridis | 6-0,5-7,10-7 |
| ITF M15 Bad Waltersdorf | 2021/08/22 09:00 | Joshua Peck v Stefanos Sakellaridis | 1-6,6-3,11-9 |
| ITF M15 Warmbad-Villach | 2021/08/17 07:30 | Lorenzo Vatteroni v Stefanos Sakellaridis | 7-6,6-2 |
| ITF M15 Warmbad-Villach | 2021/08/16 12:30 | Leon Benedict v Stefanos Sakellaridis | 4-6,3-6 |
| ITF M15 Novi Sad | 2021/08/01 14:00 | Stefanos Sakellaridis v Lukas Palovic | 4-6,1-6 |
| ITF M25 Kottingbrunn | 2021/07/18 07:30 | Stefanos Sakellaridis v Samuel Paulovcak | 1-6,4-6 |
| ITF M15 Sofia | 2021/07/05 07:00 | Stefanos Sakellaridis v Aristotelis Thanos | 2-6,6-7 |
| ITF M15 Antalya | 2021/06/30 06:30 | Hanwen Li v Stefanos Sakellaridis | 6-1,6-2 |
| ITF M15 Chornomorsk | 2021/08/30 07:00 | Maik Steiner v Myroslav Bondar | 6-4,6-0 |
| ITF M15 Novomoskovsk | 2021/05/23 10:30 | Myroslav Bondar v Aleksandr Braynin | 4-6,1-6 |