| ITF M15 Heraklion | 2021/11/10 07:00 | Guy Den Heijer v Max Houkes | 7-6,6-3 |
| UTR Pro Tennis Series Amsterdam | 2021/12/11 10:00 | Guy Den Heijer v Deney Wassermann | 6-7,7-6,1-0 |
| UTR Pro Tennis Series Amsterdam | 2021/12/10 08:25 | Rob Van Den Berg v Guy Den Heijer | 3-6,2-6 |
| UTR Pro Tennis Series Amsterdam | 2021/12/09 11:50 | Jip Van Assendelft v Guy Den Heijer | 2-6,2-6 |
| UTR Pro Tennis Series Amsterdam | 2021/12/08 10:00 | Michiel de Krom v Guy Den Heijer | 3-6,3-5 |
| UTR Pro Tennis Series Amsterdam | 2021/12/06 07:00 | Jannis Kahlke v Guy Den Heijer | 7-6,5-7,3-5 |
| ITF M15 Heraklion | 2021/11/24 08:55 | Guy Den Heijer v Arthur Fery | 6-7,2-6 |
| ITF M15 Heraklion | 2021/11/18 10:25 | Guy Den Heijer v Nicholas David Ionel | 1-6,7-5,1-6 |
| ITF M15 Heraklion | 2021/11/17 13:25 | Sergis Kyratzis v Guy Den Heijer | 6-0,4-6,4-6 |
| UTR Pro Tennis Series Amsterdam | 2021/12/11 10:00 | Tibo Colson v Max Houkes | 4-6,2-5 |
| UTR Pro Tennis Series Amsterdam | 2021/12/10 10:00 | Roland Stuurman v Max Houkes | 2-6,1-5 |
| UTR Pro Tennis Series Amsterdam | 2021/12/09 07:00 | Rik Muller v Max Houkes | 1-6,3-6 |
| UTR Pro Tennis Series Amsterdam | 2021/12/07 07:00 | Christian Hansen v Max Houkes | 6-1,3-6,2-6 |
| UTR Pro Tennis Series Amsterdam | 2021/12/06 08:30 | Max Houkes v Jesse De Jager | 4-6,6-2,6-3 |
| ITF M15 Heraklion | 2021/11/16 07:00 | Max Houkes v Kai Lemstra | 4-6,6-7 |
| ITF M15 Heraklion | 2021/11/15 08:00 | Max Houkes v Nikolas Moceanu | 6-0,6-4 |
| ITF M15 Heraklion | 2021/11/14 07:00 | Max Houkes v Stephanos Schinas | 6-2,6-4 |