Stadium: Court 4 Round: 44 Ground: Clay
| ITF Poland F6 Qual | 2018/08/05 09:30 | Guttau, Niklas v Iftimie, Michele Lorenzo | 5-7,6-2,6-3 |
| ATP Hamburg Qual | 2018/07/21 12:45 | Jozef Kovalik v Guttau, Niklas | 6-0,6-1 |
| ITF Germany F8 Qual | 2018/07/16 10:30 | Seibert, Tim v Guttau, Niklas | 6-7,7-6,6-2 |
| ITF Germany F8 Qual | 2018/07/15 12:30 | Sudzum, Marcel Marlon v Guttau, Niklas | 4-6,0-6 |
| ITF Germany F8 Qual | 2018/07/15 08:30 | Marlon Vankan v Guttau, Niklas | 1-6,2-6 |
| Challenger Braunschweig Qual | 2018/07/07 09:30 | Kimmer Coppejans v Guttau, Niklas | 6-3,6-1 |
| ITF Germany F4 | 2018/06/19 10:45 | Gonzalez, Wilfredo v Guttau, Niklas | 6-3,7-6 |
| Turkey F15, Singles Qualifying | 2018/04/14 07:30 | Guttau, Niklas v Louroi Martinez | 1-6,6-2,0-6 |
| ITF Poland F11 | 2017/08/29 09:00 | Wojnar, Bartosz v Mlazga, Krzysztof | 5-7,6-2,6-1 |
| ITF Poland F11 | 2017/08/27 08:00 | Mlazga, Krzysztof v Yatsik, Yahor | 2-6,3-6 |
| ITF Poland F10 Qual | 2017/08/20 08:00 | Mlazga, Krzysztof v Norfeldt, David | 3-6,1-6 |
| ITF Poland F6 Qual | 2017/07/16 11:00 | Bedra, Michal v Mlazga, Krzysztof | 2-6,7-6,6-3 |
| ITF Poland F5 Qual | 2017/07/09 08:00 | Mlazga, Krzysztof v Lipka, Dariusz | 2-6,2-6 |
| ITF Poland F4 Qual | 2017/07/02 08:00 | Slobodchikov, Ronald v Mlazga, Krzysztof | 6-1,7-5 |
| ITF Poland F1 | 2017/06/11 08:00 | Mlazga, Krzysztof v Ameal, Juan Ignacio | 2-6,2-6 |
| ITF Czech Republic F3 Qual | 2017/05/27 11:00 | Kristjan Tamm v Mlazga, Krzysztof | 6-3,6-3 |