Stadium: Court 4 Round: 25 Ground: Clay
| ITF M25 Denia | 2021/07/25 08:00 | Denis Klok v Lorenzo Joaquin Rodriguez | 6-7,1-6 |
| ITF M25 Gandia | 2021/07/19 09:00 | Denis Klok v Nacho Serra Sanchez | 6-7,6-0,2-10 |
| ITF M25 Gandia | 2021/07/18 07:00 | Denis Klok v Hans Albert Schubert | 6-3,6-2 |
| ITF M15 Sofia | 2021/07/07 07:00 | Denis Klok v Aleksandr Braynin | 4-6,3-6 |
| ITF M25 Belgrade | 2021/06/27 07:00 | Denis Klok v George Botezan | 3-6,1-6 |
| ITF M15 Antalya | 2021/04/28 11:40 | Francesco Maestrelli v Denis Klok | 1-6,6-2,6-1 |
| ITF M15 Antalya | 2021/04/27 07:00 | Denis Klok v Vladimir Korolev | 6-1,4-6,10-3 |
| ITF M15 Antalya | 2021/04/26 07:00 | Denis Klok v Vojtech Mares | 6-3,6-2 |
| ITF M15 Sofia | 2021/07/07 10:45 | Simon A Ivanov v Marko Miladinovic | 7-5,6-1 |
| ITF M15 Novomoskovsk | 2021/05/31 06:15 | Simon A Ivanov v Bruno P Navarro | 4-6,4-6 |
| ITF M15 Novomoskovsk | 2021/05/31 06:15 | Simon A Ivanov v Svyatoslav Ilnytskyy | 6-1,6-3 |
| ITF M15 Novomoskovsk | 2021/05/30 06:15 | Simon A Ivanov v Lorenzo Vatteroni | 6-1,6-2 |
| ITF M15 Novomoskovsk | 2021/05/25 07:00 | Simon A Ivanov v Timur Maulenov | 6-4,5-7,7-10 |
| ITF M15 Novomoskovsk | 2021/05/24 12:00 | Simon A Ivanov v Denis Constantin Spiridon | 7-6,6-1 |
| ITF M15 Novomoskovsk | 2021/05/23 08:00 | Simon A Ivanov v Leyton Rivera | 6-4,6-2 |
| ITF M15 Cairo | 2021/05/08 11:05 | Simon A Ivanov v Oliver Crawford | 7-5,6-4 |