Speaking to streamer Ibai Llanos, a Real Madrid fan, during a King's League game this week, Yamal joked that Real had a bad repuation amongst players.
"They steal, they're always complaining..." he said in jest.
Everyone on the set laughed, but the joke didn't go unnoticed. Gerard Piqué, the Barca legend and current Andorra president, agreed, stating: "There's no discussion..."
But the response from Real Madrid fans has been furious.
Journalist Edu Aguirre, who is close to Real Madrid, commented on El Chiringuito: "He doesn't realise what he represents and what he can say.
"He's 18, he's already the leader of Barça and the Spanish national team. He thinks he's the king of football. No player can say a club steals matches."
