| ITF M25 Satu Mare | 2025/05/30 08:30 | Niklas Guttau v Alex M Pujolras | 1-3 |
| ITF M25 Satu Mare | 2025/05/29 13:00 | Martin Krumich v Niklas Guttau | 6-2,4-6,6-7 |
| ITF M25 Satu Mare | 2025/05/27 07:00 | Niklas Guttau v Max Pade | 7-6,6-3 |
| German Championship | 2021/12/08 11:00 | Niklas Guttau v Michael Weindl | 4-6,6-3,1-6 |
| ITF M15 Oldenzaal | 2021/08/18 16:50 | Niklas Guttau v Niels Lootsma | 3-6,2-6 |
| ITF M15 Oldenzaal | 2021/08/17 07:30 | Nicolas Bruna v Niklas Guttau | 6-3,3-6,6-10 |
| ITF M15 Oldenzaal | 2021/08/16 10:00 | Jordi Garcia Mestre v Niklas Guttau | 4-6,1-6 |
| ITF M15 Oldenzaal | 2021/08/15 08:30 | Egill Sigurdsson v Niklas Guttau | 1-6,4-6 |