Stadium: Court 4 Round: 54 Ground: Hardcourt indoor
| ITF M15 Tallahassee | 2021/10/25 13:00 | Mattias Siimar v Sebastian Arcila | 6-3,6-3 |
| Davis Cup | 2021/09/17 13:00 | Henri Laaksonen v Mattias Siimar | 6-4,6-0 |
| ITF M15 Parnu | 2021/08/08 08:00 | Ergi Kirkin v Mattias Siimar | 5-7,6-3,6-3 |
| ITF M15 Parnu | 2021/08/07 09:00 | Mattias Siimar v Vladimir Ivanov | 6-4,3-6,6-2 |
| ITF M15 Parnu | 2021/08/05 09:45 | Mattias Siimar v Benjamin Lock | 6-3,6-4 |
| ITF M15 Parnu | 2021/08/04 10:15 | Mattias Siimar v Vilius Gaubas | 4-6,6-1,7-5 |
| ITF M15 Parnu | 2020/11/06 08:00 | Simon Freund v Mattias Siimar | 1-6,6-3,1-6 |
| ITF M15 Parnu | 2020/11/05 11:10 | Mattias Siimar v Kristjan Tamm | 6-3,6-7,6-3 |
| ITF M15 Tallahassee | 2021/10/25 13:00 | William Grant v Jake Van Emburgh | 4-6,4-6 |
| ITF M15 Naples | 2021/10/15 16:10 | Jake Van Emburgh v Juncheng Shang | 1-6,3-6 |
| ITF M15 Naples | 2021/10/14 16:00 | Dennis Novikov v Jake Van Emburgh | 3-6,6-3,3-6 |
| ITF M15 Naples | 2021/10/13 14:55 | Credit Chaiyarin v Jake Van Emburgh | 4-6,3-6 |
| ITF M15 Naples | 2021/10/06 17:25 | Jake Van Emburgh v Damien Wenger | 2-6,2-6 |
| Challenger Columbus | 2021/09/19 14:00 | Jake Van Emburgh v Alexander Sarkissian | 6-7,4-6 |
| ITF M15 Champaign | 2021/09/15 16:55 | John McNally v Jake Van Emburgh | 6-4,7-6 |
| ITF M25 Champaign | 2021/09/14 17:00 | Noah Schachter v Jake Van Emburgh | 3-6,0-6 |