On Saturday, the regular season of the Primera Federacion came to a conclusion, with Ferrol and Amorebieta securing promotion to LaLiga2 after winning Group 1 and Group 2 respectively.
The play-offs will decide the two others teams to join them in going up to the second tier of Spanish football, and one of the semi-final ties has caught the eye.
With Real Madrid Castilla finishing third in Group 1, and Barcelona Atletic finishing fourth in Group 2, it means that a mini Clasico will take place in the play-off semi-finals, in what is sure to be two hotly contested fixtures.
The first leg, with Barca Athletic at home, takes place next Sunday, with the return leg a week later. The winner will face either Celta Vigo B or Eldense in the final, with the winner of that tie progressing up to LaLiga2.
Real Sociedad, Alcorcon, Deportivo La Coruna and Castellon are in the other section of the play-offs, with those four sides fighting in out to also gain promotion.