| UTR Pro Tennis Series Zadar | 2021/11/15 12:00 | Robert Rumler v Valerii Naumenko | 6-0,6-0 |
| UTR Pro Tennis Series Portoroz | 2021/08/29 09:30 | Robert Rumler v Egor Agafonov | 7-6,6-1 |
| UTR Pro Tennis Series Portoroz | 2021/08/26 10:00 | Robert Rumler v Gal Emersic Potocnik | 6-2,6-1 |
| UTR Pro Tennis Series Portoroz | 2021/08/26 07:00 | Robert Rumler v Giacomo Revelli | 3-6,4-6 |
| UTR Pro Tennis Series Portoroz | 2021/08/25 07:00 | Robert Rumler v Paras Dahiya | 7-6,3-6,6-5 |
| ITF M25 Prostejov | 2021/08/17 07:55 | Robert Rumler v Nick Chappell | 0-6,4-6 |
| ITF M25 Grodzisk Mazowiecki | 2021/08/04 15:30 | Robert Rumler v Shintaro Mochizuki | 6-3,3-6,2-6 |
| ITF M25 Grodzisk Mazowiecki | 2021/08/02 14:10 | Robert Rumler v Piotr Galus | 7-5,7-6 |
| UTR Pro Tennis Series Zadar | 2021/11/14 12:00 | Vladimir Popov v Duje Kekez | 0-6,2-6 |
| UTR Pro Tennis Series Nis | 2021/10/09 10:15 | Alexander Lazov v Duje Kekez | 6-3,3-6,5-1 |
| UTR Pro Tennis Series Nis | 2021/10/08 17:00 | Duje Kekez v Lazar Radenkovic | 6-1,5-1 |
| UTR Pro Tennis Series Nis | 2021/10/07 14:00 | Duje Kekez v Vladimir Popov | 6-0,5-1 |
| UTR Pro Tennis Series Nis | 2021/10/06 10:00 | Ivan Denisov v Duje Kekez | 1-6,4-6 |
| UTR Pro Tennis Series Nis | 2021/10/05 11:30 | Petar Pjevcevic v Duje Kekez | 3-6,6-3,2-6 |
| UTR Pro Tennis Series Zadar | 2021/10/03 08:00 | Duje Kekez v Lawrence Bataljin | 6-1,5-1 |
| UTR Pro Tennis Series Zadar | 2021/10/02 08:30 | Duje Kekez v Jose Antonio Rodriguez Rodriguez | 0-0 |