| 3. Ronde | 01.11.2020 | Club Portugalete | - | Athletic Club B | 2:3 | ||||
| 4. Ronde | 07.11.2020 | Athletic Club B | - | SD Amorebieta | 2:1 | ||||
| 8. Ronde | 05.12.2020 | CD Laredo | - | Athletic Club B | 2:2 | ||||
| 10. Ronde | 19.12.2020 | Real Sociedad B | - | Athletic Club B | 1:2 |  |
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| 11. Ronde | 10.01.2021 | Athletic Club B | - | Real Unión | 0:0 | ||||
| 12. Ronde | 16.01.2021 | Athletic Club B | - | Arenas de Getxo | 1:1 | ||||
| 13. Ronde | 24.01.2021 | Racing Santander | - | Athletic Club B | 1:1 | ||||
| 14. Ronde | 30.01.2021 | Athletic Club B | - | Club Portugalete | 2:0 | ||||
| 15. Ronde | 06.02.2021 | SD Amorebieta | - | Athletic Club B | 2:3 | ||||
| 16. Ronde | 14.02.2021 | CD Alavés B | - | Athletic Club B | 0:2 | ||||
| 19. Ronde | 06.03.2021 | Athletic Club B | - | CD Laredo | 2:1 | ||||
| 22. Ronde | 28.03.2021 | Real Unión | - | Athletic Club B | 0:1 |
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