Rafa Benitez admitted he was shocked by referee Steve Bennett's decision to send off Javier Mascherano in Liverpool's 3-0 defeat at Manchester United.
Mascherano was shown a second yellow card for dissent just a minute before half-time with the score at 1-0.
The Argentine approached Bennett after Fernando Torres had been cautioned but Benitez insists he was merely asking the referee what had happened and was not looking to cause any trouble.
Benitez accepts that Mascherano should have been more careful but feels the dismissal killed off any chance of a Liverpool comeback.
"Clearly he didn't say anything," Benitez told Sky Sports. "I asked Ryan Babel, who was close to him. He didn't say anything, he was asking what happened.
"In a big game like this between the top four, a sending-off for asking is just a surprise."
"I was trying to say to him to calm down. Everybody knows he is fantastic professional so I was disappointed and the player was surprised.
"The player was not saying anything apart from 'what happened?'
"I have talked to him and he knows he has made a mistake."
Benitez also defended goalkeeper Jose Reina, who was at fault for Wes Brown's goal and also Cristiano Ronaldo's.
"Sometimes keepers make mistakes. These things happen," said Benitez.
"The game had finished. We had a 15-minute spell in the second half when they were feeling the pressure, but then they scored the second goal."