Stadium: Court 1 Ground: Hardcourt indoor
| Challenger Sarasota | 2019/04/15 14:00 | Harri Heliovaara v Johannes Haerteis | 6-3,6-2 |
| Challenger Drummondville | 2020/02/17 17:45 | Johannes Haerteis v Tony Bourcet | 6-2,6-0 |
| ITF M25 Nussloch | 2020/01/24 19:00 | Johannes Haerteis v Ruben Bemelmans | 4-6,3-6 |
| ITF M25 Nussloch | 2020/01/23 10:55 | Giulio Zeppieri v Johannes Haerteis | 6-3,3-6,6-7 |
| ITF M25 Nussloch | 2020/01/22 12:50 | Jakob Aichhorn v Johannes Haerteis | 2-6,6-4,4-6 |
| ITF M15 Manacor | 2020/01/15 12:35 | Johannes Haerteis v Pablo Llamas Ruiz | 3-6,4-6 |
| ITF M15 Prague | 2019/11/06 14:40 | Oleksii Krutykh v Johannes Haerteis | 4-6,7-6,6-2 |
| Challenger Eckental | 2019/10/29 09:00 | John-Patrick Smith v Johannes Haerteis | 7-6,6-7,7-6 |
| Challenger Hamburg | 2019/10/22 08:00 | Cem Ilkel v Johannes Haerteis | 7-5,6-1 |
| Challenger Launceston | 2020/02/03 23:00 | Harri Heliovaara v Michail Pervolarakis | 3-6,3-6 |
| Challenger Burnie | 2020/01/26 23:00 | Takuto Niki v Harri Heliovaara | 6-4,1-6,7-6 |
| Challenger Helsinki | 2019/11/15 14:00 | Harri Heliovaara v Ilya Ivashka | 6-3,1-6,2-6 |
| Challenger Helsinki | 2019/11/14 11:00 | Hugo Grenier v Harri Heliovaara | 1-6,3-6 |
| Challenger Helsinki | 2019/11/13 11:00 | Harri Heliovaara v Hiroki Moriya | 4-6,7-6,6-3 |
| Challenger Helsinki | 2019/11/11 16:10 | Artem Dubrivnyy v Harri Heliovaara | 3-6,2-6 |
| Challenger Playford 2 | 2019/10/30 23:30 | Jay Clarke v Harri Heliovaara | 6-4,6-3 |
| Challenger Playford 2 | 2019/10/29 23:30 | Harri Heliovaara v Mukund Sasikumar | 7-6,6-3 |