Stadium: Court 3 Round: 27 Ground: Hardcourt indoor
| ITF M15 - East Lansing | 2021/11/18 20:00 | Ronald Hohmann v Alex Knaff | 3-6,4-6 |
| ITF M15 - East Lansing | 2021/11/17 18:00 | William Bushamuka v Alex Knaff | 2-6,6-7 |
| ITF M15 - East Lansing | 2021/11/16 16:00 | Joshua Sheehy v Alex Knaff | 3-6,2-6 |
| ITF M15 - Ithaca | 2021/11/04 13:55 | Felix Corwin v Alex Knaff | 5-7,7-6,7-5 |
| ITF M15 - Ithaca | 2021/11/03 15:30 | Radu Mihai Papoe v Alex Knaff | 6-4,3-6,0-6 |
| ITF M15 - Tallahassee | 2021/10/27 13:55 | Alex Knaff v Sho Shimabukuro | 4-6,6-4,4-6 |
| ITF M15 - Tallahassee | 2021/10/26 13:00 | Blu Baker v Alex Knaff | 6-7,5-7 |
| ITF M15 - Tallahassee | 2021/10/25 13:00 | Alex Knaff v Matthew Dellavedova | 6-4,6-2 |
| ITF M15 - East Lansing | 2021/11/18 18:00 | Alexandre Rotsaert v Colin Sinclair | 5-7,6-4,2-6 |
| ITF M15 - East Lansing | 2021/11/17 20:45 | Nico Mostardi v Colin Sinclair | 3-6,4-6 |
| ITF M15 - Ithaca | 2021/11/04 16:45 | Colin Sinclair v Vasil Kirkov | 3-6,4-6 |
| ITF M15 - Ithaca | 2021/11/03 17:55 | Michael Zheng v Colin Sinclair | 0-6,2-6 |
| ITF M15 - Tallahassee | 2021/10/27 14:00 | Colin Sinclair v Ryan Shane | 6-3,3-6,6-7 |
| ITF M15 - Ithaca | 2021/10/05 16:00 | Taha Baadi v Colin Sinclair | 7-6,7-5 |
| ITF M25 - Budapest | 2021/09/28 10:45 | Pawel Juszczak v Colin Sinclair | 6-2,7-6 |
| UTR Pro Tennis Series - Mülheim | 2021/09/25 13:30 | Colin Sinclair v Guy Den Heijer | 2-6,3-5 |