| Davis Cup | 2020/03/07 12:40 | Frederik Nielsen v Ignacio Garcia | 7-6,6-2 |
| ATP New York | 2020/02/09 20:30 | Go Soeda v Frederik Nielsen | 6-1,6-2 |
| Challenger Phoenix | 2019/03/13 18:40 | Frederik Nielsen v Peter Polansky | 6-7,3-6 |
| Challenger Phoenix | 2019/03/11 17:00 | Frederik Nielsen v Fabrice Martin | 6-4,7-6 |
| Challenger Noumea | 2018/12/31 04:05 | Daniel Masur v Frederik Nielsen | 6-1,5-7,6-4 |
| Challenger Fairfield | 2018/10/08 17:00 | Kevin King v Frederik Nielsen | 6-4,6-3 |
| Challenger Fairfield | 2018/10/07 18:15 | Thai-Son Kwiatkowski v Frederik Nielsen | 7-6,3-6,5-7 |
| Challenger Fairfield | 2018/10/06 22:15 | Frederik Nielsen v Roberto Ortega-Olmedo | 6-2,6-2 |