| ITF M25 Eupen | 2021/09/09 09:00 | Romain Faucon v Guy Den Heijer | 6-4,6-4 |
| ITF M25 Eupen | 2021/09/08 07:30 | Guy Den Heijer v Kai Wehnelt | 3-6,6-3,6-2 |
| ITF M25 Eupen | 2021/09/07 10:05 | Guy Den Heijer v Tom Gentzsch | 6-3,6-4 |
| ITF M25 Eupen | 2021/09/06 14:45 | Guy Den Heijer v Yannick Lenaerts | 6-1,6-0 |
| ITF M15 Oldenzaal | 2021/08/21 10:10 | Guy Den Heijer v Damien Wenger | 4-6,2-6 |
| ITF M15 Oldenzaal | 2021/08/20 16:35 | Guy Den Heijer v Alexander Hoogmartens | 6-3,6-7,6-4 |
| ITF M15 Oldenzaal | 2021/08/20 10:20 | Sander Jong v Guy Den Heijer | 5-7,7-5,4-6 |
| ITF M15 Oldenzaal | 2021/08/18 12:35 | Vladimir Ivanov v Guy Den Heijer | 6-4,4-6,4-6 |
| ITF M15 Ulcinj | 2021/09/13 13:00 | Daisuke Sumizawa v Deney Wassermann | 6-4,7-6 |
| ITF M15 Ulcinj | 2021/09/13 08:00 | Eric Morris v Deney Wassermann | 4-6,6-3,8-10 |
| ITF M15 Huy | 2021/08/27 13:00 | Alexis Gautier v Deney Wassermann | 6-1,6-4 |
| ITF M15 Huy | 2021/08/26 14:10 | Deney Wassermann v Marvin Netuschil | 6-3,6-2 |
| ITF M15 Huy | 2021/08/24 15:35 | Martin Katz v Deney Wassermann | 4-6,1-6 |
| ITF M15 Oldenzaal | 2021/08/18 07:55 | Alexander Hoogmartens v Deney Wassermann | 2-6,7-6,6-0 |
| ITF M15 Esch/Alzette | 2021/07/22 13:05 | Deney Wassermann v Patrick Kypson | 2-6,3-6 |
| ITF M15 Esch/Alzette | 2021/07/21 11:10 | Wilson Leite v Deney Wassermann | 6-3,1-6,3-6 |