| 1. Round | 14/08/2020 | NK Opatija | - | Hajduk Split II | 2:1 | ||||
| 2. Round | 22/08/2020 | NK Sesvete | - | NK Opatija | 0:1 |  |
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| 4. Round | 12/09/2020 | NK Rudeš | - | NK Opatija | 1:2 | |
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| 5. Round | 15/09/2020 | NK Opatija | - | HNK Cibalia | 0:1 | ||||
| 6. Round | 19/09/2020 | NK Dubrava | - | NK Opatija | 1:4 | |
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| 3. Round | 23/09/2020 | NK Opatija | - | NK Solin | 1:1 | ||||
| 7. Round | 27/09/2020 | NK Opatija | - | HNK Orijent Rijeka | 1:1 |  |
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| 8. Round | 30/09/2020 | Hrvatski Dragovoljac | - | NK Opatija | 1:1 | ||||
| 9. Round | 03/10/2020 | NK Opatija | - | NK Osijek II | 1:1 | ||||
| 10. Round | 17/10/2020 | NK Junak Sinj | - | NK Opatija | 0:2 | |
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| 12. Round | 30/10/2020 | NK Međimurje | - | NK Opatija | 3:0 | ||||
| 11. Round | 14/11/2020 | NK Opatija | - | NK Dugopolje | 2:1 | ||||
| 14. Round | 21/11/2020 | NK Kustošija | - | NK Opatija | 2:1 | ||||
| 13. Round | 25/11/2020 | NK Opatija | - | NK Inter Zaprešić | 3:2 | |
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| 15. Round | 28/11/2020 | NK Opatija | - | NK Croatia Zmijavci | 2:3 | |
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| 17. Round | 13/12/2020 | NK BSK Bijelo Brdo | - | NK Opatija | 1:1 | |
Croatia