Barcelona and Real Madrid's Clasico meeting on October 26 could be moved from Camp Nou to the Bernabeu, with La Liga fearing that planned protests over Catalan independence will affect the fixture.
The authorities in charge of Spain's top division have spoken to both clubs and made a formal request that the match be reversed, meaning Madrid would host the first meeting between the two rivals this season.
Should the clubs agree, that would mean the return fixture, due to be played in March 2020, would be hosted at Camp Nou instead.
A statement from the Royal Spanish Football Federation (RFEF) read: "RFEF has received the LFP request and has brought the case to the Competition Committee, which has brought the situation to the clubs.
"FC Barcelona and Real Madrid have until Monday to respond. After [their comments] are received and analysed, the Competition will decide."
The request comes amid clashes between Catalan residents and police over the region's independence from Spain, with a big demonstration due to be held on the same day as the Clasico meeting at Camp Nou.
Chaotic scenes in the city ensued following the sentencing of nine Catalan separatist leaders on Monday, with prison terms of between nine and 13 years having been issued by Spain's Supreme Court.
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