Stadium: Court 12 Round: 62
| ITF M25 Alkmaar | 2021/06/20 17:00 | Alec Deckers v Guy Den Heijer | 3-6,7-6,4-10 |
| ITF M25 Vic | 2021/05/16 08:00 | Mateus Alves v Guy Den Heijer | 6-2,6-3 |
| ITF M15 Valldoreix | 2021/05/09 13:00 | Guy Den Heijer v Pol Amoros Ramos | 3-6,2-6 |
| ITF M15 Majadahonda | 2021/05/02 16:15 | Taiyo Yamanaka v Guy Den Heijer | 6-7,6-3,11-9 |
| ITF M15 Antalya | 2021/03/25 07:00 | Guy Den Heijer v Juan Pablo Paz | 1-6,2-6 |
| ITF M15 Antalya | 2021/03/24 06:30 | Guy Den Heijer v Carlo Alberto Fossati | 6-2,6-3 |
| ITF M15 Antalya | 2021/03/22 07:00 | Guy Den Heijer v Vladislav Gorbatenko | 7-5,6-0 |
| ITF M15 Antalya | 2021/03/21 07:00 | Guy Den Heijer v Alexander Ovcharov | 6-1,6-2 |
| ITF M15 Monastir | 2021/04/11 09:00 | Lorenzo Bresciani v Samir Hamza Reguig | 6-1,6-4 |
| ITF M15 Monastir | 2021/04/04 11:30 | Albert Roglan v Samir Hamza Reguig | 6-1,6-1 |
| ITF M15 Monastir | 2021/03/29 09:00 | Samir Hamza Reguig v Anas Fattar | 2-6,5-7 |
| ITF M15 Monastir | 2021/03/28 08:00 | Facundo Yunis v Samir Hamza Reguig | 7-5,5-7,3-10 |
| ITF M15 Monastir | 2021/03/17 11:55 | Christian Langmo v Samir Hamza Reguig | 6-0,2-6,6-3 |
| ITF M15 Monastir | 2021/03/09 08:30 | Aziz Ouakaa v Samir Hamza Reguig | 3-6,6-4,6-1 |
| ITF M15 Monastir | 2021/02/28 09:00 | Stefano Battaglino v Samir Hamza Reguig | 6-2,6-2 |
| ITF M15 Monastir | 2021/02/22 12:30 | Omar Giacalone v Samir Hamza Reguig | 6-3,6-1 |