| UTR Pro Tennis Series Amsterdam | 2021/11/06 12:00 | Deney Wassermann v Guy Den Heijer | 2-6,5-6 |
| UTR Pro Tennis Series Amsterdam | 2021/11/05 13:30 | Guy Den Heijer v Johann Willems | 7-6,2-6,6-4 |
| UTR Pro Tennis Series Amsterdam | 2021/11/03 10:30 | Guy Den Heijer v Lawrence Bataljin | 6-0,6-3 |
| 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 | 2021/11/01 13:30 | Miko Wassermann v Guy Den Heijer | 2-6,5-7 |
| ITF M15 Girona | 2021/10/19 08:00 | Guy Den Heijer v Vladislav Ivanov | 6-4,6-3 |
| ITF M15 Girona | 2021/10/18 08:00 | Guy Den Heijer v Samir Hamza Reguig | 6-2,6-1 |
| ITF M15 Girona | 2021/10/17 08:00 | Guy Den Heijer v Ervin H Eminefendic | 6-3,6-1 |
| UTR Pro Tennis Series Amsterdam | 2021/11/06 13:30 | Thorsten Sollie v Sem Verbeek | 6-4,4-6,5-7 |
| UTR Pro Tennis Series Amsterdam | 2021/11/05 10:30 | Sem Verbeek v Mikhail Minakov | 6-2,6-3 |
| UTR Pro Tennis Series Amsterdam | 2021/11/03 12:00 | Sem Verbeek v Benjamin Dhoe | 6-3,6-4 |
| UTR Pro Tennis Series Amsterdam | 2021/11/02 13:30 | Sem Verbeek v Amadatus Admiraal | 6-2,6-2 |
| UTR Pro Tennis Series Amsterdam | 2021/11/01 10:30 | Tom Clavel v Sem Verbeek | 6-2,4-6,4-6 |
| Challenger Porto | 2021/06/29 16:40 | Sem Verbeek v Gastao Elias | 7-6,4-6,1-6 |
| Challenger Porto | 2021/06/28 10:00 | Sem Verbeek v Francisco Cabral | 7-6,6-3 |
| Challenger Porto | 2021/06/27 13:10 | Mukund Sasikumar v Sem Verbeek | 6-3,3-6,5-7 |