The big match kicks off at 16:15 CET (15:15 in the UK), which means it falls under the times football cannot be televised live in England and Scotland.
That is due to the 3pm blackout, with the rule stating that no football games can be broadcast live on television between 2:45pm and 5:15pm on a Saturday.
The law was introduced in the 1960s and was designed to protect football attendances across the country.
It remains because Article 48 of UEFA's statutes allows member nations to choose a two-and-a-half hour window during the weekend in which no football matches are broadcast live.
Only England, Scotland and Montenegro currently adhere to the 3pm blackout rule and many have called for it to be scrapped.
While it was widely believed that the law covered only English games, it applies to any football fixtures televised in this country.
That means El Clasico cannot be broadcast live on Saturday, with the game to be shown in full and delayed by Viaplay from 17:25 in the UK on Saturday.
"We’re disappointed that British fans cannot watch El Clasico this weekend due to the UK's self- imposed Saturday 3pm rule," said Keegan Pierce, La Liga's Head of International Development for UK and Ireland MD.
"While we fully support measures to promote attendance, we believe the blackout should be limited to the televising of domestic football, not overseas competitions."
More LaLiga stories
Real Madrid forward Vinicius Junior has called for a crackdown on racism in Spain after he received fresh abuse in last weekend's LaLiga clash at Sevilla.
Watch Barcelona's 17-year-old striker Marc Gui net the winner for the Catalan club in last Sunday's LaLiga game at home to Athletic Club – after just 30 seconds on the pitch!
Meanwhile, Arsenal captain Martin Odegaard has said that leaving Real Madrid was 'the best decision' for him and his career.
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