Stadium: Court 8 Round: 25 Ground: Clay
| ITF M25 Wetzlar | 2021/08/06 15:55 | Constantin Schmitz v Peter Heller | 3-6,7-5,1-6 |
| ITF M25 Wetzlar | 2021/08/05 13:55 | Dayne Kelly v Constantin Schmitz | 2-6,1-6 |
| ITF M25 Wetzlar | 2021/08/04 12:30 | Constantin Schmitz v Jannik Rother | 6-2,6-0 |
| ITF M15 Troisdorf | 2021/05/12 09:00 | Constantin Schmitz v Tom Kocevar-Desman | 6-4,4-6,3-6 |
| ITF M15 Antalya | 2021/04/14 10:30 | Ivan Sergeyev v Constantin Schmitz | 6-3,5-7,6-3 |
| ITF M15 Antalya | 2021/04/08 06:55 | Flavio Cobolli v Constantin Schmitz | 7-6,7-6 |
| ITF M15 Antalya | 2021/04/06 07:00 | Constantin Schmitz v Bogdan Bobrov | 6-1,6-4 |
| ITF M15 Antalya | 2021/03/30 08:30 | Pol Martin Tiffon v Constantin Schmitz | 6-4,7-6 |
| ITF M25 Frankfurt am Main | 2021/08/12 09:00 | Mick Veldheer v Oriol Roca Batalla | 4-6,6-2,4-6 |
| ITF M15 Frederiksberg | 2021/08/06 12:40 | Mick Veldheer v August Holmgren | 4-6,4-6 |
| ITF M15 Frederiksberg | 2021/08/05 10:00 | Mick Veldheer v Palaphoom Kovapitukted | 0-6,6-3,6-3 |
| ITF M15 Frederiksberg | 2021/08/04 11:05 | Mick Veldheer v Philip Hjorth | 6-3,6-3 |
| ITF M15 Vejle | 2021/07/29 16:30 | Guy Den Ouden v Mick Veldheer | 6-4,6-0 |
| ITF M15 Vejle | 2021/07/28 12:45 | Gabriel Decamps v Mick Veldheer | 3-6,1-6 |
| ITF M15 Esch/Alzette | 2021/07/22 09:55 | Nicholas David Ionel v Mick Veldheer | 7-6,1-6,6-4 |
| ITF M15 Esch/Alzette | 2021/07/21 11:50 | Marlon Vankan v Mick Veldheer | 3-6,6-0,6-7 |