Manchester City boss Manuel Pellegrini launched an astonishing attack on referee Jonas Eriksson after the 2-0 defeat by Barcelona, accusing him of being "not impartial" and suggesting UEFA had made a mistake in appointing an official from Sweden.
The comments are set to land City's manager in serious trouble with UEFA, especially after he suggested that Eriksson was trying to make up for making an error against Barcelona in a previous match against AC Milan.
Pellegrini's statement overshadowed a game which was decided by Lionel Messi's penalty, which led to Martin Demichelis' dismissal, and Dani Alves' last-minute strike.
The City manager said: "From the beginning I felt the referee was not impartial to both teams so he decided the game with a foul that he didn't whistle against and a penalty with Demichelis that was not a penalty, it was outside the box.
"He did not have any control of the game. He was on the side of Barcelona from the beginning until the end.
"I think it was not a good idea to put a referee from Sweden in charge of such an important match, especially a referee who has made an important mistake against Barcelona in a previous match."
Pellegrini appeared to be referring to the 2012 Champions League quarter-final when Eriksson was criticised by then-Barcelona coach Pep Guardiola for failing to award his side two penalties in the first-leg's goalless draw at the San Siro.
"This referee whistled the Barcelona-Milan and he made an important error against Barcelona. Today he rearranged it," said the City boss.
Pellegrini claimed Eriksson should have given City a free-kick in the build-up to the move that led to the penalty award for a foul on Jesus Navas.
He added: "I think that the referee decided the game because before the penalty there was a foul on Navas three metres away from him so he could see it without any problem.
"The more important mistake is the foul against Navas and secondly the penalty.
"Contact was outside the box - that is the foul, you cannot continue the foul. The first foul is outside the box.
"Before the penalty Barcelona did not have chances and we were preparing the way to score.
"Playing 40 minutes with one player less is very difficult against Barcelona. We played well and tried to draw and in the last minute they scored the second goal."
The Chilean was asked to explain his comments that UEFA should not have chosen a referee from Sweden.
He replied: "More important football in Europe than Sweden. A big game with two important teams, that kind of game needs a referee with more experience."
Pellegrini confronted Eriksson after the final whistle to express his displeasure.
"It was just to tell him that I was not very happy because he decided the game," said the City manager.
Barcelona midfielder Cesc Fabregas was pleased the Spanish giants could "prove a point" to some of their doubters following a dip in form over the last month and he was delighted they could "shut up" their critics.
Chelsea boss Jose Mourinho had called the Catalan side "the worst Barcelona of many years" and former Arsenal star Fabregas told ITV: "Maybe we had to prove a point in a way and I think we did it and I think we did it in a style and very, very well, but this team has done so much and won so much to always have to prove a point.
"But today was one of those days maybe everyone was saying Barcelona was not the same Barcelona...some people were talking a bit too much and as usual they will have to shut up for a few days.
"We are top of the league, we had a good result and we are in the final of the [Copa del Rey]. There's nothing else you can ask for.
"But the fans in Spain in general put the most pressure on you as a team - the fans and everyone - and that's what makes everyone feel so special to this team."
Barcelona head coach Tata Martino refused to get carried away by the first-leg result, pointing out that City had beaten Bayern Munich away from home in the group stage.
He said: "I am not confident but we have had a good game away from home and we just have to repeat the same performance.
"We must not forget that City lost to Bayern Munich at home and then they won away."
He also refused to be drawn on Mourinho's criticism, saying: "What people say outside games is just a waste of time. We just have to play well in every competition."