The Argentina captain went to the players’ car park at the Bernabéu in search of Álvaro Arbeloa after the game.
Messi reportedly launched a tirade of insults at the Real defender – calling him “stupid”, to name but one – leaving the full-back completely shocked.
Arbeloa’s wife, Carlota, who is expecting a baby, was said to be with the Spain international and was also astonished.
“What’s his problem?” she asked her husband, according to witnesses at the scene. A Barcelona member of staff had to be called to take Messi to the team coach.
La Sexta television and La Cope radio also reported another incident involving the Barça goal-machine and another member of the Real setup – Aitor Karanka, which occurred in the tunnel to the changing rooms.