Barcelona captain Lionel Messi admits Javier Mascherano can lose his rag.

Messi makes the revelation in the forward he wrote for his teammate's new book:

"He has his days.

“Sometimes he comes in [to training] wanting to make jokes and chat, but he also has his crazy days.

"When that's the case, it's better not to talk to him. We see him arrive and nobody dares say anything."