Referee Jose Maria Sanchez Martinez has included in his report why he sent off Barcelona coach Xavi on Sunday.
Xavi saw red before halftime as Barca won 3-0 at Atletico Madrid.
Sanchez Martinez wrote post-match: "He made technical observations on one of my decisions, loudly, making inconsiderate gestures and after having been previously warned by the fourth referee."
Xavi said post-match: "This is the least important thing, the important thing is the team. The fourth referee told me that it is because of the gestures. I haven't said anything, I'm trying to be passionate. I live it, I want my team to win. The expulsion was unnecessary and unfair, but you have to accept it.
"I haven't spoken to the referee."