| UTR Pro Tennis Series Mulheim | 2021/10/15 08:30 | Jing L Weng v Constantin Schmitz | 0-6,4-5 |
| UTR Pro Tennis Series Mulheim | 2021/10/14 10:00 | Yurii Dzhavakian v Constantin Schmitz | 4-6,5-7 |
| UTR Pro Tennis Series Mulheim | 2021/10/12 08:30 | Edison Ambarzumjan v Constantin Schmitz | 2-6,2-5 |
| UTR Pro Tennis Series Mulheim | 2021/10/11 07:00 | Constantin Schmitz v Tim Sandkaulen | 6-4,7-5 |
| ITF M15 Allershausen | 2021/08/31 11:25 | Constantin Schmitz v Mick Veldheer | 6-7,4-6 |
| ITF M25 Trier | 2021/08/26 09:30 | Constantin Schmitz v Ryan Nijboer | 4-6,2-6 |
| ITF M25 Trier | 2021/08/25 11:40 | Mats Rosenkranz v Constantin Schmitz | 1-6,1-6 |
| ITF M15 Oldenzaal | 2021/08/19 12:35 | Constantin Schmitz v Luke Johnson | 7-5,0-6,3-6 |
| UTR Pro Tennis Series Mulheim | 2021/10/15 11:30 | Eric Vanshelboim v Johann Willems | 2-6,4-6 |
| UTR Pro Tennis Series Mulheim | 2021/10/14 08:30 | Diego Balderas v Johann Willems | 0-6,2-6 |
| UTR Pro Tennis Series Mulheim | 2021/10/12 07:00 | Ivan Marrero Curbelo v Johann Willems | 2-6,3-5 |
| UTR Pro Tennis Series Mulheim | 2021/10/11 12:15 | Johann Willems v Benjamin Dhoe | 6-2,5-1 |
| UTR Pro Tennis Series Mulheim | 2021/09/23 09:30 | Johann Willems v Alen Moritz Hodzic | 0-0 |
| UTR Pro Tennis Series Mulheim | 2021/09/20 08:00 | Johann Willems v Maxence Broville | 0-0 |
| German Premier League | 2020/07/27 17:05 | Paul Valsecchi v Johann Willems | 1-6,7-5,6-2 |
| ITF M15 Monastir | 2020/03/09 13:30 | Johann Willems v Paras Dahiya | 3-6,6-2,6-10 |