| UTR Pro Tennis Series Zadar | 2021/07/02 12:30 | de La Bassetiere, Constant v Jerko Brkic | 7-6,5-2 |
| UTR Pro Tennis Series Zadar | 2021/07/01 09:30 | Sinius, Warren v Jerko Brkic | 6-3,6-5 |
| UTR Pro Tennis Series Zadar | 2021/06/30 08:00 | Krstanovic, Josip v Jerko Brkic | 6-4,5-3 |
| UTR Pro Tennis Series Zadar | 2021/06/28 12:30 | Nincevic, Frane v Jerko Brkic | 6-1,7-5 |
| Challenger - Split | 2021/04/04 13:20 | Lukas Klein v Jerko Brkic | 6-1,6-2 |
| ITF - M15 Porec | 2020/03/08 08:00 | Jerko Brkic v Gorazd Srbljak | 2-6,6-7 |
| ITF Hungary F5 Qual | 2017/06/18 08:00 | Jerko Brkic v Petr Nouza | 2-6,3-6 |
| ITF Croatia F4 Qual | 2017/03/25 10:00 | Jerko Brkic v Aguilar, Federico Juan | 2-6,6-3,4-6 |
| UTR Pro Tennis Series Zadar | 2021/07/03 11:30 | Ihor Dudun v Kajin, Karlo | 3-6,1-6 |
| UTR Pro Tennis Series Zadar | 2021/07/01 11:00 | Kajin, Karlo v Matija Pecotic | 1-6,2-5 |
| UTR Pro Tennis Series Zadar | 2021/06/30 09:30 | Kajin, Karlo v Kiefer, Alexander | 3-6,1-6 |
| UTR Pro Tennis Series Zadar | 2021/06/29 12:30 | Kajin, Karlo v Khomich, Aleksei | 6-4,3-6,2-6 |
| UTR ProTennis Series Zadar | 2021/06/28 08:00 | Kajin, Karlo v Goetz, Ryan | 1-6,1-5 |
| ITF Croatia F3 | 2018/03/19 12:30 | Gabrieli, Tommaso v Kajin, Karlo | 7-6,6-4 |
| ITF Croatia F3 | 2018/03/18 10:30 | de Rosa, Marco v Kajin, Karlo | 6-7,6-2,2-6 |
| ITF Croatia F2 | 2018/03/12 08:00 | Andres Gabriel Ciurletti v Kajin, Karlo | 6-3,6-3 |