Stadium: Court 5 Round: 44 Ground: Clay
| ATP Hamburg Qual | 2018/07/21 12:45 | Jozef Kovalik v Niklas Guttau | 6-0,6-1 |
| ITF Germany F8 Qual | 2018/07/16 10:30 | Tim Seibert v Niklas Guttau | 6-7,7-6,6-2 |
| ITF Germany F8 Qual | 2018/07/15 12:30 | Marcel Marlon Sudzum v Niklas Guttau | 4-6,0-6 |
| ITF Germany F8 Qual | 2018/07/15 08:30 | Marlon Vankan v Niklas Guttau | 1-6,2-6 |
| Challenger Braunschweig Qual | 2018/07/07 09:30 | Kimmer Coppejans v Niklas Guttau | 6-3,6-1 |
| ITF Germany F4 | 2018/06/19 10:45 | Wilfredo Gonzalez v Niklas Guttau | 6-3,7-6 |
| ITF Turkey F15 | 2018/04/14 07:30 | Niklas Guttau v Louroi Martinez | 1-6,6-2,0-6 |
| ITF Turkey F14 | 2018/04/07 11:00 | Niklas Guttau v Lucas Hellfritsch | 4-6,3-6 |
| ITF France F13 Qual | 2018/07/08 15:55 | Joshua Paris v Michele Lorenzo Iftimie | 6-1,7-5 |
| ITF France F13 Qual | 2018/07/07 07:30 | Michele Lorenzo Iftimie v Enzo Frequelin | 3-6,6-2,6-3 |
| Challenger Recanati Qual | 2018/06/30 13:30 | Michele Lorenzo Iftimie v Francesco Ferrari | 3-6,2-6 |