| ITF - M15 Doha | 2021/10/11 13:30 | Boris Butulija v Nikolaj Katic | 6-1,6-3 |
| ITF - M15 Doha - Calificari | 2021/10/10 15:45 | Theertha Shashank Macherla v Nikolaj Katic | 4-6,6-7 |
| ITF - M15 Doha | 2021/10/04 12:00 | Nikolaj Katic v Tao Mu | 0-6,1-6 |
| ITF - M15 Doha | 2021/10/03 13:20 | Alexey Dubinin v Nikolaj Katic | 2-6,1-6 |
| ITF - M25 Falun | 2021/09/26 11:00 | Nikolaj Katic v Daniel Little | 6-7,4-6 |
| ITF - M25 Jonkoping | 2021/09/19 11:00 | Ben Jones v Nikolaj Katic | 6-2,6-7,10-6 |
| UTR Pro Tennis Series - Ricany | 2021/09/08 09:00 | Nikolaj Katic v Jiri Barnat | 1-6,0-2 |
| UTR Pro Tennis Series - Ricany | 2021/09/07 13:00 | Nikolaj Katic v Maxence Broville | 3-6,3-6 |
| ITF - M25 Sintra | 2021/09/13 16:30 | Henrik Heise Korsgaard v Jip Van Assendelft | 6-3,4-6,5-10 |
| ITF - M25 Sintra | 2021/09/07 10:45 | Alastair Gray v Henrik Heise Korsgaard | 6-1,6-4 |
| ITF - M25 Sintra | 2021/09/06 13:30 | Paulo A S Dos Santos v Henrik Heise Korsgaard | 7-5,5-7,6-10 |
| ITF - M15 Vejle | 2021/07/29 14:35 | Henrik Heise Korsgaard v Christian Sigsgaard | 7-5,6-2 |
| ITF - M15 Vejle | 2021/07/27 17:20 | Leonardo Catani v Henrik Heise Korsgaard | 3-6,3-6 |
| UTR Pro Tennis Series - Copenhaga | 2021/06/19 08:30 | Dominik Palan v Henrik Heise Korsgaard | 6-7,5-2 |
| UTR Pro Tennis Series - Copenhaga | 2021/06/18 08:00 | Henrik Atlevi v Henrik Heise Korsgaard | 0-6,3-6 |
| UTR Pro Tennis Series - Copenhaga | 2021/06/17 08:00 | Maxim Landa v Henrik Heise Korsgaard | 1-6,4-6 |