Stadium: Court 3 Round: 45 Ground: Hardcourt indoor
| Challenger Bastad Qual | 2018/07/07 10:40 | Lammons, Nathaniel v Taylor, Sam | 6-4,3-6,4-6 |
| Challenger Loughborough Qual | 2018/05/19 10:35 | Alexis Canter v Lammons, Nathaniel | 6-3,7-6 |
| Challenger Lisbon Qual | 2018/05/13 12:20 | Vega Hernandez, David v Lammons, Nathaniel | 6-2,3-6,6-2 |
| Challenger Lisbon Qual | 2018/05/12 11:40 | Goncalo Falcao v Lammons, Nathaniel | 6-2,5-7,4-6 |
| Challenger Savannah Qual | 2018/04/28 18:35 | Karue Sell v Lammons, Nathaniel | 6-4,6-4 |
| Challenger Tallahassee Qual | 2018/04/21 17:30 | Lammons, Nathaniel v Yoshihito Nishioka | 2-6,0-6 |
| Challenger Tallahassee Qual | 2018/04/21 14:00 | Lammons, Nathaniel v Galloway, Robert | 7-5,6-4 |
| Challenger Panama City Qual | 2018/03/31 22:45 | Lammons, Nathaniel v Franco Agamenone | 2-6,4-6 |
| Challenger Charlottesville | 2018/10/27 18:30 | Ymer, Mikael v Nguyen, Daniel | 3-6,6-2,6-4 |
| Challenger Las Vegas | 2018/10/20 17:00 | Nguyen, Daniel v Thai-Son Kwiatkowski | 2-6,3-6 |
| Challenger Fairfield | 2018/10/07 18:20 | King, Kevin v Nguyen, Daniel | 6-2,6-0 |
| Challenger Fairfield | 2018/10/06 21:30 | Nguyen, Daniel v Kelly, Dayne | 6-3,7-5 |
| Challenger Stockton | 2018/09/29 22:00 | Nguyen, Daniel v Harris, Andrew | 0-6,4-6 |
| Challenger Tiburon | 2018/09/22 20:15 | Nguyen, Daniel v Hiltzik, Jared | 4-6,7-6,1-6 |
| ITF Japan F2 | 2018/03/18 02:00 | Nguyen, Daniel v Tung-Lin Wu | 6-7,7-6,7-6 |
| ITF Japan F2 | 2018/03/17 03:45 | Kaichi Uchida v Nguyen, Daniel | 6-4,3-6,3-6 |