Stadium: Court C Round: 62 Ground: Clay
| ITF M25 Meerbusch | 2021/04/12 09:30 | Marvin Netuschil v Kai Lemstra | 6-2,6-3 |
| ITF M15 Monastir | 2021/03/15 12:30 | Kai Lemstra v Alexander Kotzen | 1-6,3-6 |
| ITF M15 Monastir | 2021/03/15 08:00 | Kai Lemstra v John Sperle | 6-3,6-3 |
| ITF M15 Monastir | 2021/03/14 08:00 | Guy Orly Iradukunda v Kai Lemstra | 3-6,5-7 |
| ITF M15 Monastir | 2021/03/11 10:40 | Kai Lemstra v Juan Bautista Torres | 4-6,1-6 |
| ITF M15 Monastir | 2021/03/10 12:15 | Kai Lemstra v Christoph Negritu | 6-4,2-6,6-1 |
| ITF M15 Monastir | 2021/03/08 18:00 | Anis Ghorbel v Kai Lemstra | 6-3,6-4 |
| ITF M15 Monastir | 2021/03/08 13:30 | Sabit Suntic v Kai Lemstra | 3-6,6-4,8-10 |