Stadium: Swiss Post Court Round: 62 Ground: Clay
| 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 - Oldenzaal | 2021/08/17 09:15 | Guy Den Heijer v Alexis Canter | 6-4,6-4 |
| ITF M15 - Oldenzaal | 2021/08/16 10:00 | Guy Den Heijer v Noel Larwig | 6-3,6-4 |
| ITF M15 - Oldenzaal | 2021/08/15 14:00 | Guy Den Heijer v Paulo Knippling | 6-3,6-4 |
| ITF M25 - Eupen | 2021/09/06 13:30 | Nico Hornitschek v Tom Gentzsch | 4-6,4-6 |
| ITF M25 - Eupen | 2021/09/05 07:30 | Tom Gentzsch v Olivier Rojas | 6-3,7-5 |
| ITF M25 - Trier | 2021/08/25 09:00 | Tom Gentzsch v Ryan Nijboer | 3-6,4-6 |
| ITF M25 - Trier | 2021/08/23 13:30 | Paul Valsecchi v Tom Gentzsch | 5-7,3-6 |
| ITF M25 - Prostejov | 2021/08/16 07:55 | Simon Malis v Tom Gentzsch | 6-4,5-7,10-8 |
| ITF M25 - Prostejov | 2021/08/15 08:00 | Tomas Krcma v Tom Gentzsch | 0-6,2-6 |
| Challenger Meerbusch | 2021/08/08 08:00 | Jesper De Jong v Tom Gentzsch | 6-1,6-3 |
| ITF M15 - Skopje | 2021/06/01 08:00 | Niels Visker v Tom Gentzsch | 6-4,6-1 |