Stadium: Court 1 Round: 54 Ground: Hardcourt indoor
| ITF - M15 Selva Gardena | 2021/10/24 10:45 | Kai Lemstra v Davide Ferrarolli | 6-4,6-3 |
| ITF - M25 Hamburg | 2021/10/17 07:55 | Tom Schonenberg v Kai Lemstra | 6-2,6-2 |
| ITF - M15 Monastir | 2021/08/26 07:30 | Kai Lemstra v Renta Tokuda | 2-6,2-6 |
| ITF - M15 Monastir | 2021/08/25 07:30 | Hamzeh Al-Aswad v Kai Lemstra | 2-6,1-6 |
| ITF - M15 Monastir | 2021/08/24 07:30 | Seita Watanabe v Kai Lemstra | 1-6,1-6 |
| ITF - M15 Monastir | 2021/08/23 09:00 | Alec Beckley v Kai Lemstra | 3-6,2-6 |
| ITF - M15 Monastir | 2021/08/22 12:00 | Lucca Pinto v Kai Lemstra | 3-6,0-6 |
| ITF - M15 Monastir | 2021/08/18 09:00 | Kai Lemstra v Duarte Vale | 4-6,3-6 |
| ITF - M15 Selva Gardena | 2021/10/24 11:20 | Nicolo Toffanin v Dominique Graf | 3-6,4-6 |
| ITF - M25 Hamburg | 2021/10/17 09:55 | Adrian Obert v Dominique Graf | 6-1,7-6 |
| ITF - M25 Praha | 2021/10/03 14:00 | Antonin Bolardt v Dominique Graf | 6-2,6-2 |
| ITF - M25 Pardubice | 2021/09/19 11:00 | Matyas Cerny v Dominique Graf | 7-6,6-3 |
| ITF - M25 Poznan | 2021/08/24 08:00 | Dominique Graf v Svyatoslav Ilnytskyy | 6-4,2-6,10-6 |
| ITF - M25 Poznan | 2021/08/22 08:00 | Taiyo Yamanaka v Dominique Graf | 7-6,1-6,8-10 |
| ITF - M25 Prostějov | 2021/08/17 11:40 | Lucas Miedler v Dominique Graf | 6-4,6-2 |
| ITF - M25 Prostějov | 2021/08/16 08:00 | Dominique Graf v Jakub Kroslak | 6-2,6-4 |