Jurgen Klopp believes referee Felix Brych had a personal issue with Sadio Mane as Liverpool fell in a 3-1 loss to Real Madrid on Tuesday night.
The Reds were comfortably beaten by Los Blancos in the first leg of the Champions League quarter-finals.
Vinicius Junior opened the scoring, before Marco Asensio doubled Real Madrid’s lead in the 36th minute as Mane appeared to be fouled by Lucas Vazquez in preparation for the second goal.
The Liverpool forward was booked for dissent three minutes later and Klopp was unhappy with his player’s treatment.
He said: “The situation with Sadio, what the referee did tonight, I have to say I don’t understand.
“For me it was something personal because he handled the situation with Sadio, which was a clear fault, like he was a diver or whatever.
“From that point on, every time Sadio fell, he got nothing. It’s not correct. That’s what I told him after the game, that I thought he was unfair to Sadio.
“It doesn’t change anything at all. It [Brych] did not lose the game. We weren’t good enough to get a better result, but at times like these you just need an “okay” referee. It would have been enough.
Klopp admitted Liverpool deserved to lose on the night as Mohamed Salah’s away goal gave them hope of saving the draw at Anfield.
He added: “First and foremost, I don’t think we deserved to win tonight, we didn’t play well enough and that’s my number one concern.
“Especially in the first half, we didn’t play football well enough. We conceded the first goal, served the second on a plate, but that wasn’t the real problem of the game.
“Of course conceding goals is a problem, but it’s not the problem. The second half we did better, we scored our goal which is the positive of the evening and that’s how it is.
“Did we deserve more than the 3-1?” I am not sure.”