Stadium: Pista 2 Round: 25 Ground: Hardcourt outdoor
| Challenger Hamburg | 2019/10/22 08:00 | Cem Ilkel v Johannes Haerteis | 7-5,6-1 |
| Wimbledon | 2021/06/22 14:45 | Tomas Martin Etcheverry v Cem Ilkel | 6-1,6-4 |
| Challenger Forli | 2021/06/15 11:35 | Orlando Luz v Cem Ilkel | 7-5,3-6,7-5 |
| Challenger Bratislava | 2021/06/11 13:35 | Filip Horansky v Cem Ilkel | 6-3,6-4 |
| Challenger Bratislava | 2021/06/10 09:00 | Cem Ilkel v Facundo Mena | 6-3,6-4 |
| Challenger Bratislava | 2021/06/08 12:10 | Elliot Benchetrit v Cem Ilkel | 5-7,2-6 |
| French Open | 2021/05/25 16:00 | Cem Ilkel v Mohamed Safwat | 4-6,4-6 |
| Challenger Biella | 2021/05/17 12:50 | Cem Ilkel v Bjorn Fratangelo | 2-6,4-6 |
| Challenger Rome | 2021/05/01 13:00 | Cem Ilkel v Flavio Cobolli | 3-6,5-7 |
| Challenger Amersfoort | 2021/07/13 08:30 | Mats Moraing v Johannes Haerteis | 6-1,6-0 |
| Challenger Braunschweig | 2021/07/04 11:55 | Johannes Haerteis v Nino Ehrenschneider | 6-3,3-6,4-6 |
| Challenger Prostejov | 2021/06/15 08:30 | Johannes Haerteis v Federico Coria | 1-6,0-6 |
| Challenger Prostejov | 2021/06/14 08:30 | Johannes Haerteis v David Poljak | 5-7,3-6 |
| Challenger Prostejov | 2021/06/13 09:00 | Johannes Haerteis v Jakub Nicod | 6-3,3-6,6-3 |
| Challenger Bratislava | 2021/06/06 14:15 | Skander Mansouri v Johannes Haerteis | 6-3,7-5 |
| Challenger Oeiras | 2021/05/25 14:00 | Johannes Haerteis v Filip Cristian Jianu | 3-6,0-6 |
| Challenger Ortisei | 2020/11/19 10:00 | Johannes Haerteis v Ilya Ivashka | 6-7,3-6 |