Stadium: Court 6 Round: 46 Ground: Hardcourt outdoor
| Challenger Fairfield | 2018/10/06 22:15 | Marcos Giron v Thai-Son Kwiatkowski | 6-4,2-6,4-6 |
| Challenger Stockton | 2018/10/03 20:00 | Lloyd Harris v Thai-Son Kwiatkowski | 6-2,6-4 |
| Challenger Stockton | 2018/10/01 18:35 | Thai-Son Kwiatkowski v Lucas Miedler | 3-6,7-6,6-4 |
| Challenger Columbus | 2018/09/21 16:45 | Mikael Torpegaard v Thai-Son Kwiatkowski | 6-4,6-2 |
| Challenger Columbus | 2018/09/19 19:35 | Thai-Son Kwiatkowski v Peter Polansky | 7-6,2-6,7-6 |
| Challenger Columbus | 2018/09/18 16:45 | Vincent Millot v Thai-Son Kwiatkowski | 2-6,4-6 |
| Challenger Columbus | 2018/09/17 14:00 | Thai-Son Kwiatkowski v Joris De Loore | 3-6,6-4,7-6 |
| Challenger Columbus | 2018/09/16 14:00 | Thai-Son Kwiatkowski v Ricardo Rodriguez-Pace | 6-1,6-3 |
| Challenger Fairfield | 2018/10/06 22:15 | Frederik Nielsen v Roberto Ortega-Olmedo | 6-2,6-2 |
| Challenger Stockton | 2018/09/29 23:05 | Alexander Ritschard v Frederik Nielsen | 6-4,7-6 |
| Challenger Tiburon | 2018/09/22 18:15 | Frederik Nielsen v Alexander Sarkissian | 4-6,5-7 |
| Challenger Cary | 2018/09/08 18:20 | Frederik Nielsen v Evan Song | 2-6,6-7 |
| Challenger Chicago | 2018/09/02 22:00 | Kaichi Uchida v Frederik Nielsen | 6-3,6-4 |
| Challenger Chicago | 2018/09/02 15:00 | Joris De Loore v Frederik Nielsen | 6-7,6-2,5-7 |
| Challenger Portoroz | 2018/08/07 08:00 | Lucas Miedler v Frederik Nielsen | 6-3,6-2 |
| Challenger Portoroz Qual | 2018/08/06 08:00 | Frederik Nielsen v Albano Olivetti | 6-2,7-6 |