Mourinho sat stonefaced beside assistant Aitor Karanka, who answered questions. Mourinho's refusal to speak led to a number of journalists walking out of the news conference in protest.
Karanka says: "It's a way of working ... it's not a lack of respect toward anyone."
Karanka has taken questions instead of Mourinho 11 times this season but this was the second straight league game where the Portuguese coach did not speak in the buildup.
Barcelona leads Madrid by eight points before the game at the Santiago Bernabeu Stadium.
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