The Clasico between Barcelona and Real Madrid has been postponed due to protests in Catalonia, the Spanish Football Federation (RFEF) said.
The clubs have until 1100 EAT on Monday to find a new date, which will be decided by the RFEF if the clubs cannot reach an agreement.
The original fixture was due to take place at Barca's Camp Nou on October 26.
"FC Barcelona and Real Madrid must agree on the new date of the meeting before October 21," an RFEF statement read.
"In case of not reaching an agreement, the Competition Committee will be responsible for determining the date of the meeting."
The Spanish football league (LFP) on Wednesday said it had asked the RFEF to move the fixture from Barcelona to Madrid after three days of large-scale demonstrations which have turned increasingly violent.