Stadium: Espoo Metro Areena Round: 4 Ground: Hardcourt indoor
| Challenger Warsaw | 2021/08/22 09:00 | Christopher Heyman v Patrik Niklas-Salminen | 6-1,6-3 |
| ITF M15 Bratislava | 2021/08/17 13:40 | Matvey Minin v Patrik Niklas-Salminen | 6-1,7-6 |
| ITF M15 Gdynia | 2021/08/10 14:10 | Alexis Musialek v Patrik Niklas-Salminen | 6-4,6-3 |
| ITF M15 Parnu | 2021/08/04 08:30 | Patrik Niklas-Salminen v Yan Sabanin | 3-6,6-7 |
| Challenger Tampere | 2021/07/19 16:05 | Patrik Niklas-Salminen v Alexandre Muller | 2-6,1-6 |
| ITF M15 Nur-Sultan | 2021/02/10 04:45 | Patrik Niklas-Salminen v Oscar Weightman | 6-4,4-6,2-6 |
| ITF M15 Nur-Sultan | 2021/02/04 05:00 | Otto Virtanen v Patrik Niklas-Salminen | 6-2,6-3 |
| ITF M15 Nur-Sultan | 2021/02/03 09:05 | Francesco Maestrelli v Patrik Niklas-Salminen | 3-6,2-6 |
| Davis Cup | 2021/09/17 14:50 | Otto Virtanen v Prajnesh Gunneswaran | 6-3,7-6 |
| Challenger Saint-Tropez | 2021/08/30 12:25 | Prajnesh Gunneswaran v Hugo Grenier | 5-7,3-6 |
| US Open | 2021/08/26 18:20 | Christopher Eubanks v Prajnesh Gunneswaran | 6-3,6-4 |
| US Open | 2021/08/25 15:00 | Brayden Schnur v Prajnesh Gunneswaran | 4-6,6-7 |
| ATP Washington | 2021/08/03 18:00 | Prajnesh Gunneswaran v Emil Ruusuvuori | 6-2,1-6,1-6 |
| ATP Washington | 2021/08/01 19:30 | Prajnesh Gunneswaran v Go Soeda | 6-3,6-1 |
| ATP Washington | 2021/07/31 16:00 | Prajnesh Gunneswaran v Luke Saville | 6-2,6-2 |
| Challenger Lexington | 2021/07/27 18:00 | Prajnesh Gunneswaran v Peter Polansky | 3-6,4-6 |