Stadium: Teremeer (4) Round: 25 Ground: Hardcourt outdoor
| ITF M15 Sibenik | 2021/04/21 12:05 | Gergely Madarasz v Yannick Mertens | 6-4,5-7,6-3 |
| ITF M25 Meerbusch | 2021/04/15 10:00 | Alexander Erler v Yannick Mertens | 6-3,3-6,6-1 |
| ITF M25 Meerbusch | 2021/04/13 13:30 | Yannick Mertens v Jeroen Vanneste | 6-3,6-4 |
| ITF M15 Monastir | 2021/03/11 08:30 | Yannick Mertens v Naoki Nakagawa | 6-4,3-6,4-6 |
| ITF M15 Monastir | 2021/03/10 10:30 | Yannick Mertens v Constantin Schmitz | 6-0,6-2 |
| ITF M15 Monastir | 2021/02/13 08:30 | Yannick Mertens v Gauthier Onclin | 6-3,1-6,2-6 |
| ITF M15 Monastir | 2021/02/12 10:05 | Yannick Mertens v Juan Bautista Torres | 6-2,6-3 |
| ITF M15 Monastir | 2021/02/11 08:25 | Yannick Mertens v Lukas Mugevicius | 6-1,6-1 |
| ITF M25 Meerbusch | 2021/04/11 14:00 | Hugo Voljacques v Max Wiskandt | 4-6,6-1,10-0 |
| ITF M15 Poitiers | 2021/03/18 09:30 | Martin Breysach v Max Wiskandt | 6-2,6-7,6-4 |
| ITF M15 Poitiers | 2021/03/17 09:00 | Oscar Moraing v Max Wiskandt | 3-6,7-6,0-6 |
| ITF M15 Monastir | 2021/02/14 10:00 | Antonio Massara v Max Wiskandt | 6-4,6-4 |
| ITF M15 Monastir | 2021/02/08 11:45 | Antonio Massara v Max Wiskandt | 7-6,3-6,10-6 |
| ITF M15 Monastir | 2021/02/07 14:30 | Max Wiskandt v Taiyo Yamanaka | 2-6,7-5,11-9 |
| German Championship | 2020/12/09 12:00 | Timo Stodder v Max Wiskandt | 6-4,6-4 |
| German Championship | 2020/12/08 08:00 | Nils Brinkmann v Max Wiskandt | 7-6,3-6,4-6 |