Stadium: Court 2 Round: 25 Ground: Hardcourt outdoor
| Turkey F14, Singles Qualifying | 2018/04/07 11:00 | Guttau, Niklas v Hellfritsch, Lucas | 4-6,3-6 |
| ITF - M15 Sharm El Sheikh | 2019/11/19 09:45 | Hellfritsch, Lucas v Boerma, Pelle | 6-7,6-4,11-9 |
| ITF - M15 Sharm El Sheikh | 2019/11/10 11:00 | Hellfritsch, Lucas v Catini, Daniele | 6-7,4-6 |
| ITF - M15 Antalya | 2019/10/23 08:30 | Slobodchikov, Ronald v Hellfritsch, Lucas | 6-3,6-3 |
| ITF - M15 Antalya | 2019/10/22 07:00 | Emesz, Benedikt v Hellfritsch, Lucas | 6-7,3-6 |
| ITF - M15 Antalya | 2019/10/21 07:00 | Virgili, Augusto v Hellfritsch, Lucas | 4-6,6-4,8-10 |
| ITF - M15 Antalya | 2019/10/20 09:00 | Gusev, Daniil v Hellfritsch, Lucas | 1-6,1-6 |
| ITF - M15 Antalya | 2019/10/02 07:00 | Marsel Ilhan v Hellfritsch, Lucas | 6-2,6-2 |
| ITF - M15 Antalya | 2019/10/01 07:00 | Hellfritsch, Lucas v Kempen, Lynn Max | 6-4,6-3 |
| ITF - M15 Sharm El Sheikh | 2019/11/14 09:20 | Giorgio Ricca v Guttau, Niklas | 6-2,4-6,7-6 |
| ITF - M15 Sharm El Sheikh | 2019/11/13 11:40 | Hasenkopf, Mariano Alberto v Guttau, Niklas | 3-6,5-7 |
| ITF - M15 Sharm El Sheikh | 2019/11/06 12:35 | Guttau, Niklas v Sidane Pontjodikromo | 3-6,2-6 |
| Challenger Eckental | 2019/10/29 11:40 | Maxime Cressy v Guttau, Niklas | 6-3,7-5 |
| Challenger - Hambourg | 2019/10/22 09:40 | Jelle Sels v Guttau, Niklas | 7-6,6-2 |
| Tabarka, Singles Qualifying M-ITF-TUN-41A | 2019/10/09 09:55 | Guttau, Niklas v Alexander Weis | 6-7,2-6 |
| Tabarka, Singles Qualifying M-ITF-TUN-41A | 2019/10/02 08:30 | Guttau, Niklas v Bogdan Bobrov | 0-6,6-3,4-6 |
| Tabarka, Singles Qualifying M-ITF-TUN-41A | 2019/09/26 08:30 | Dambrosi, Giacomo v Guttau, Niklas | 5-7,6-4,6-3 |