Fans have been absent from matches in the top two tiers of Spanish football since March 2020 with the original final date of April 18, 2020 cancelled due to the coronavirus pandemic.
Both clubs were offered the chance to play behind closed doors in August, however, the Basque rivals opted to decline the option to play without fans.
According to reports from Marca, the rescheduled final could be the first game that permits fans to attend, with a provisional date of April 4, 2021 at the Estadio La Cartuja in Sevilla.
La Liga president Javier Tebas has consistently stated his intention to bring fans back into stadiums as soon as possible, but a previous estimation of early January 2021 is likely to be missed.
Supporters have returned to limited stadiums in the English Premier League this weekend, with the situation set to be reviewed in Spain later this month.