| UTR Pro Tennis Series Zadar | 2021/06/30 08:00 | Josip Krstanovic v Jerko Brkic | 6-4,5-3 |
| UTR Pro Tennis Series Zadar | 2021/06/29 11:00 | Josip Krstanovic v Constant De La Bassetiere | 1-6,6-3,6-6 |
| UTR Pro Tennis Series Zadar | 2021/06/28 12:30 | Warren Sinius v Josip Krstanovic | 2-6,1-5 |
| ITF M15 Sibenik | 2021/04/19 10:00 | Mehdi Sadaoui v Josip Krstanovic | 7-6,6-4 |
| ITF M15 Sibenik | 2021/04/18 10:00 | Josip Krstanovic v Pavle Daljev | 6-4,6-3 |
| ITF M15 Opatija | 2021/03/21 11:00 | Oleksandr Ovcharenko v Josip Krstanovic | 6-4,6-0 |
| ITF M15 Rovinj | 2021/03/15 11:00 | Josip Krstanovic v Federico Arnaboldi | 1-6,2-6 |
| ITF M15 Rovinj | 2021/03/14 08:30 | Josip Krstanovic v Mattia Frinzi | 6-2,7-6 |
| UTR Pro Tennis Series Zadar | 2021/07/01 09:30 | Constant De La Bassetiere v Frane Nincevic | 3-6,2-6 |
| UTR Pro Tennis Series Zadar | 2021/06/29 11:00 | Warren Sinius v Frane Nincevic | 5-7,3-6 |
| UTR Pro Tennis Series Zadar | 2021/06/28 12:30 | Frane Nincevic v Jerko Brkic | 6-1,7-5 |
| ITF M15 Sarajevo | 2021/06/02 09:00 | Frane Nincevic v Mathieu Perchicot | 6-2,2-6,4-6 |
| ITF M15 Sibenik | 2021/05/17 08:00 | Nikola Basic v Frane Nincevic | 6-7,6-1,10-8 |
| Challenger Zagreb | 2021/05/09 08:30 | Frane Nincevic v Ramkumar Ramanathan | 4-6,3-6 |
| ITF M15 Sibenik | 2021/04/21 08:00 | Sebastian Prechtel v Frane Nincevic | 6-0,6-3 |
| Challenger Split Qual | 2021/04/11 12:25 | Frane Nincevic v Tristan Lamasine | 1-6,5-7 |