| UTR Pro Tennis Series - Portoroz | 2021/08/29 08:00 | Olexiy Kolisnyk v Deni Zmak | 4-6,6-2,6-3 |
| UTR Pro Tennis Series - Portoroz | 2021/08/27 12:00 | Olexiy Kolisnyk v Domen Gostincar | 7-6,6-3 |
| UTR Pro Tennis Series - Portoroz | 2021/08/25 10:00 | Olexiy Kolisnyk v Volodymyr Uzhylovskyi | 6-1,6-1 |
| UTR Pro Tennis Series - Portoroz | 2021/08/25 07:00 | Olexiy Kolisnyk v Vladan Tadic | 6-2,3-6,2-1 |
| UTR Pro Tennis Series - Portoroz | 2021/08/24 08:30 | Nik Razborsek v Olexiy Kolisnyk | 5-7,6-2,2-6 |
| UTR Pro Tennis Series - Portoroz | 2021/08/21 09:30 | Olexiy Kolisnyk v Deni Zmak | 4-6,6-7 |
| UTR Pro Tennis Series - Portoroz | 2021/08/20 11:00 | Olexiy Kolisnyk v Lawrence Bataljin | 6-3,6-2 |
| UTR Pro Tennis Series - Portoroz | 2021/08/18 08:00 | George Botezan v Olexiy Kolisnyk | 5-7,1-6 |
| UTR Pro Tennis Series - Nis | 2021/10/10 08:00 | Christos Keisidis v Vladimir Popov | 6-1,5-2 |
| UTR Pro Tennis Series - Nis | 2021/10/09 11:00 | Christos Keisidis v Lawrence Bataljin | 6-4,6-2 |
| UTR Pro Tennis Series - Nis | 2021/10/08 15:45 | Dusan Trunic v Christos Keisidis | 2-6,2-5 |
| UTR Pro Tennis Series - Nis | 2021/10/07 08:30 | George Botezan v Christos Keisidis | 6-3,6-3 |
| UTR Pro Tennis Series - Nis | 2021/10/05 14:00 | Aleksa Mardjonovic v Christos Keisidis | 2-6,7-5,6-4 |
| UTR Pro Tennis Series - Nis | 2021/10/04 11:30 | Christos Keisidis v Alexander Lazov | 6-3,0-6,3-6 |
| UTR Pro Tennis Series - Zadar | 2021/10/03 09:30 | Admir Kalender v Christos Keisidis | 6-2,6-0 |
| UTR Pro Tennis Series - Zadar | 2021/10/02 11:30 | Christos Keisidis v Ivan Denisov | 3-6,6-1,6-5 |