Stadium: Court 3 Round: 25 Ground: Clay
| ITF M25 Trimbach | 2021/03/09 14:40 | Yannik Steinegger v Alexander Erler | 4-6,4-6 |
| ITF M15 Caslano | 2020/08/31 08:55 | Alexander Erler v Yannik Steinegger | 4-6,3-6 |
| Challenger Prostejov | 2021/06/16 10:05 | Dalibor Svrcina v Alexander Erler | 6-1,7-5 |
| Challenger Prostejov | 2021/06/14 08:30 | Alexander Erler v Pavel Nejedly | 7-5,6-3 |
| Challenger Prostejov | 2021/06/13 11:10 | Alexander Erler v Jakub Mensik | 6-3,6-4 |
| ITF M25 Most | 2021/05/27 07:55 | Alexander Erler v Franco Agamenone | 4-6,0-6 |
| ITF M25 Most | 2021/05/25 09:35 | Alexander Erler v Jean Thirouin | 7-5,7-6 |
| ITF M15 Antalya | 2021/05/16 07:30 | Alexander Erler v Nick Hardt | 0-6,6-7 |
| ITF M15 Antalya | 2021/05/15 07:30 | Orlando Luz v Alexander Erler | 6-4,6-7,2-6 |
| ITF M15 Antalya | 2021/05/14 09:50 | Alexander Erler v Timofey Skatov | 4-6,6-2,6-1 |
| ITF M25 Klosters | 2021/06/21 07:00 | Davide Tortora v Yannik Steinegger | 5-7,3-6 |
| ITF M25 Klosters | 2021/06/20 08:40 | Johann Lars v Yannik Steinegger | 2-6,4-6 |
| ITF M15 Gaiba | 2021/06/08 11:20 | Giorgio Ricca v Yannik Steinegger | 6-3,5-7,10-7 |
| ITF M15 Gaiba | 2021/06/07 15:25 | Giovanni Agostinetto v Yannik Steinegger | 4-6,3-6 |
| ITF M15 Helsinki | 2021/06/03 07:00 | Yannik Steinegger v Bruno Kuzuhara | 2-6,6-2,3-6 |
| ITF M15 Helsinki | 2021/06/02 11:30 | Mikhail Minakov v Yannik Steinegger | 4-6,1-6 |
| ITF M15 Helsinki | 2021/06/01 08:50 | Yannik Steinegger v Alexander Chepik | 6-4,6-3 |
| ITF M15 Helsinki | 2021/05/31 10:00 | Yannik Steinegger v Peetu Pohjola | 6-2,6-3 |