Stadium: Court 17 Round: 25 Ground: Clay
| 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 |
| ITF M15 Skopje | 2021/05/31 08:00 | Tom Gentzsch v Louis Allen | 7-6,2-6,13-11 |
| ITF M15 Skopje | 2021/05/30 07:00 | Aloys J W Van Baal v Tom Gentzsch | 1-6,7-5,7-10 |
| ITF M15 Heraklion | 2021/05/17 07:00 | Milan Welte v Tom Gentzsch | 6-0,6-3 |
| ITF M15 Oldenzaal | 2021/08/19 12:45 | Alexander Hoogmartens v Ryan Nijboer | 1-6,7-5,6-3 |
| ITF M15 Oldenzaal | 2021/08/18 12:45 | Alec Deckers v Ryan Nijboer | 6-3,2-6,4-6 |
| ITF M15 Frederiksberg | 2021/08/05 10:00 | Ryan Nijboer v Benjamin Hannestad | 1-6,6-4,2-6 |
| ITF M15 Frederiksberg | 2021/08/04 09:25 | Ryan Nijboer v Leyton Rivera | 6-4,6-2 |
| ITF M15 Vejle | 2021/07/28 12:50 | Christian Sigsgaard v Ryan Nijboer | 6-3,6-2 |
| Challenger Amersfoort | 2021/07/13 10:15 | Ryan Nijboer v Johan Nikles | 6-7,2-6 |
| ITF M25 Marburg | 2021/07/10 11:00 | Ryan Nijboer v Nick Hardt | 2-6,4-6 |
| ITF M25 Marburg | 2021/07/09 12:00 | Ryan Nijboer v Milan Welte | 4-6,6-3,6-1 |