| 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 |
| ATP Hamburg | 2021/07/10 09:00 | Carlos Taberner v Niklas Guttau | 6-1,6-2 |
| ITF M15 Antalya | 2021/04/11 07:00 | Edoardo Graziani v Niklas Guttau | 6-4,6-1 |
| ITF M15 Antalya | 2021/04/06 07:00 | Niklas Guttau v Edoardo Graziani | 2-6,3-6 |
| ITF M15 Antalya | 2021/04/05 07:00 | Niklas Guttau v Tomas Lanik | 6-2,6-2 |
| ITF M15 Heraklion | 2021/11/11 10:30 | Michael Weindl v Peter Fajta | 6-3,6-7,6-7 |
| ITF M15 Heraklion | 2021/11/10 08:30 | Simon A Ivanov v Michael Weindl | 7-5,1-6,1-6 |
| ITF M15 Heraklion | 2021/11/01 09:00 | Michael Weindl v Ioannis Papounidis | 3-6,6-2,3-10 |
| Challenger Ismaning | 2021/10/24 10:35 | Matthias Bachinger v Michael Weindl | 6-1,6-3 |
| ITF M15 Allershausen | 2021/09/01 09:00 | Dominik Boehler v Michael Weindl | 1-6,6-1,6-2 |
| ITF M15 Allershausen | 2021/08/31 08:00 | Anirudh Chandrasekar v Michael Weindl | 2-6,3-6 |
| ITF M25 Trimbach | 2021/03/08 09:00 | Jonas Schaer v Michael Weindl | 7-6,5-7,11-9 |
| ITF M15 Antalya | 2021/01/11 07:00 | Calin Manda v Michael Weindl | 7-6,6-2 |