Round: 25 Ground: Hardcourt outdoor
| ITF Great Britain F6 | 2016/11/12 11:00 | Alastair Gray v Frederik Nielsen | 3-6,3-6 |
| 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 |
| Challenger St Brieuc Qual | 2017/03/27 14:35 | Frederik Nielsen v Egor Gerasimov | 7-6,2-6,0-6 |
| Challenger St Brieuc Qual | 2017/03/26 14:00 | Gregoire Jacq v Frederik Nielsen | 5-7,6-7 |
| ITF Spain F17 | 2017/06/12 07:30 | Alastair Gray v Santiago Plaza | 2-6,7-5,6-4 |
| ITF Spain F17 | 2017/06/11 09:00 | Alastair Gray v Alvaro Blanco Damea | 6-1,6-4 |
| ITF USA F13 | 2017/04/12 16:20 | Alastair Gray v Eric Quigley | 3-6,2-6 |
| ITF USA F13 Qual | 2017/04/10 16:30 | Alastair Gray v Austen Huang | 5-7,7-5,6-4 |
| ITF USA F13 Qual | 2017/04/09 15:00 | Alastair Gray v Stratton Gilmore | 6-2,6-0 |
| ITF USA F13 Qual | 2017/04/08 15:00 | Alastair Gray v Jason Lui | 6-3,6-2 |
| ITF USA F11 Qual | 2017/03/20 16:00 | Gage Brymer v Alastair Gray | 6-4,6-4 |
| ITF USA F11 Qual | 2017/03/19 16:00 | Patrick Davidson v Alastair Gray | 3-6,3-6 |