| UTR Pro Tennis Series Amsterdam | 2021/11/02 10:30 | Guy Den Heijer v Jip Van Assendelft | 6-4,5-2 |
| UTR Pro Tennis Series Amsterdam | 2021/12/08 07:00 | Jip Van Assendelft v Rob Van Den Berg | 4-6,6-4,6-1 |
| UTR Pro Tennis Series Amsterdam | 2021/12/07 10:00 | Jip Van Assendelft v Jannis Kahlke | 2-6,7-5,6-2 |
| UTR Pro Tennis Series Amsterdam | 2021/12/06 07:00 | Jip Van Assendelft v Michiel de Krom | 2-6,6-2,1-6 |
| UTR Pro Tennis Series Amsterdam | 2021/11/07 09:00 | Benjamin Dhoe v Jip Van Assendelft | 3-6,4-5 |
| UTR Pro Tennis Series Amsterdam | 2021/11/06 16:00 | Nathan De Veer v Jip Van Assendelft | 2-6,3-5 |
| UTR Pro Tennis Series Amsterdam | 2021/11/05 09:00 | Jip Van Assendelft v Lawrence Bataljin | 7-6,6-2 |
| UTR Pro Tennis Series Amsterdam | 2021/11/04 12:00 | Jip Van Assendelft v Johann Willems | 3-6,2-5 |
| UTR Pro Tennis Series Amsterdam | 2021/11/03 09:00 | Miko Wassermann v Jip Van Assendelft | 1-6,4-5 |
| 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 Irákleio | 2021/11/24 08:55 | Guy Den Heijer v Arthur Fery | 6-7,2-6 |
| ITF M15 Irákleio | 2021/11/18 10:25 | Guy Den Heijer v Nicholas David Ionel | 1-6,7-5,1-6 |
| ITF M15 Irákleio | 2021/11/17 13:25 | Sergis Kyratzis v Guy Den Heijer | 6-0,4-6,4-6 |
| ITF M15 Irákleio | 2021/11/11 07:00 | Guy Den Heijer v Alec Deckers | 4-6,6-7 |
| ITF M15 Irákleio | 2021/11/10 07:00 | Guy Den Heijer v Max Houkes | 7-6,6-3 |
| UTR Pro Tennis Series Amsterdam | 2021/11/07 10:30 | Guy Den Heijer v Sem Verbeek | 6-3,6-3 |