The Segunda Division promotion picture will not be confirmed until the final day of the 2020/21 season.
The Catalans have the edge in the race to be crowned as champions with a one point lead at the top of the table ahead of their trip to Alcorcon.
The play off line up is almost complete with just one place left to be clinched on the final day of the 42-game season.
Rayo have a one-point advantage going into the final weekend with a home game against relegation battling Lugo with Sporting Gijon at home to rivals Almeria.
A win would be enough for Rayo to clinch a play-off place but a draw and a Gijon victory would see them miss out.