| ITF M15 Pittsburgh | 2022/07/12 14:00 | Christian Lakoseljac v John Mercer | 6-3,6-2 |
| ITF M15 South Bend | 2022/06/21 12:30 | Presley Thieneman v John Mercer | 6-3,6-4 |
| UTR Pro Tennis Series Florida | 2021/12/15 15:30 | Matthew Segura v John Mercer | 6-1,6-3 |
| UTR Pro Tennis Series Florida | 2021/12/13 17:00 | Shunsuke Mitsui v John Mercer | 6-1,6-0 |
| ITF M15 East Lansing | 2021/11/16 15:00 | John Mercer v Nico Mostardi | 1-6,5-7 |
| ITF M15 East Lansing | 2021/11/15 18:00 | Matthew Dellavedova v John Mercer | 6-7,2-6 |
| ITF M25 Fayetteville | 2019/10/22 14:45 | Murphy Cassone v John Mercer | 6-3,2-6,10-8 |
| ITF M25 Fayetteville | 2019/10/21 15:00 | John Mercer v Ian Chadwell | 6-4,6-4 |