Round: 25 Ground: Hardcourt outdoor
| ITF Spain F17 | 2017/06/15 18:45 | Frederik Nielsen v Alberto Barroso Campos | 6-4,2-6,1-6 |
| ITF Spain F17 | 2017/06/13 19:40 | Frederik Nielsen v Alastair Gray | 6-2,6-4 |
| Challenger Busan Qual | 2017/05/14 03:10 | Austin Krajicek v Frederik Nielsen | 6-3,6-2 |
| Challenger Busan Qual | 2017/05/13 03:45 | Bradley Mousley v Frederik Nielsen | 4-6,3-6 |
| Challenger Seoul Qual | 2017/05/06 01:00 | Frederik Nielsen v Felix Auger Aliassime | 1-6,4-6 |
| Challenger Gimcheon Qual | 2017/04/29 05:15 | Lloyd Glasspool v Frederik Nielsen | 6-7,6-2,6-2 |
| Davis Cup | 2017/04/09 10:00 | Casper Ruud v Frederik Nielsen | 4-6,2-6,3-6 |
| Davis Cup | 2017/04/07 16:15 | Viktor Durasovic v Frederik Nielsen | 2-6,6-3,2-6,6-7 |
| ITF Hungary F4 | 2017/06/15 11:35 | Constant Lestienne v Marek Gengel | 6-1,7-5 |
| ITF Hungary F4 | 2017/06/13 12:10 | Bartosz Wojnar v Marek Gengel | 0-6,4-6 |
| ITF Czech Republic F3 | 2017/05/31 08:30 | Michal Marko v Marek Gengel | 7-6,4-6,6-4 |
| ITF Czech Republic F1 | 2017/05/17 08:30 | Adrian Obert v Marek Gengel | 6-2,6-4 |
| Challenger Ostrava Qual | 2017/04/30 08:00 | Sebastian Ofner v Marek Gengel | 7-5,6-0 |
| Challenger Ostrava Qual | 2017/04/29 11:25 | Marek Gengel v Victor-Mugurel Anagnastopol | 6-3,6-1 |
| ITF Egypt F12 | 2017/04/06 08:00 | Marek Gengel v David Pichler | 3-6,6-7 |
| ITF Egypt F12 | 2017/04/05 09:30 | Marek Jaloviec v Marek Gengel | 4-6,6-4,5-7 |