Premier League bosses including Jurgen Klopp, Mauricio Pochettino and Ange Postecoglou came out against the International Football Association Board (IFAB) plan to introduce a blue card on Friday as part of trials to introduce sin bins in professional football.
The trial is designed to assess whether temporary dismissals for dissent and specific tactical offences such as so-called 'professional' fouls -- where a player deliberately takes out an opponent in an attacking situation when a red card isn't warranted -- can improve player behaviour and increase respect for match officials.
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Sources have since told ESPN that the blue card element of the sin bin trial has been postponed by IFAB.
Liverpool manager Jurgen Klopp said that he thinks officiating should be made more simple for referees.
"These kinds of things just make it more complicated," Klopp told a news conference. "If you want to test it, no problem with testing, but if that's the first step to agreeing or already being sure that it will happen. I have no idea to be honest. I have no idea.
"[It] doesn't sound like a fantastic idea in first moment. But I can't remember when the last fantastic idea came from these guys [IFAB] if they ever had one.
Tottenham head coach Ange Postecoglou questioned the wisdom behind the trial.
"I struggle to understand why this urgency suddenly to bring in new things. I don't know if there's that much wrong with the game," Postecoglou said.
"My issue with the game right now is that VAR has changed football as an experience. I don't know why a different colour card is going to make a difference. I don't know about this taking things from other sports. Other sports are trying to make their games faster, we're bringing in more clutter."
Chelsea boss Mauricio Pochettino said that he wants to know how the blue card would be applied in different match situations, and added that he would have been shown "a lot" if they had been introduced while he was still playing.
"It's going to be more complicated because the interpretation of the referee [of] when to apply the red, the yellow or the blue [is important]," Pochettino said.
"What happens with the goalkeeper? Do you play without the goalkeeper for 10 minutes or can you change? We will see.
Arsenal manager Mikel Arteta said he could see the potential benefits of the proposed new law.
"I think everything is being done with the intention to simplify it and make it more clear and try to cut out mistakes from decisions that are extremely difficult," Arteta told a news conference.
"In a split second, you are talking about centimetres, or even millimetres. So hopefully everything is done to improve the game, and if that's the case. It's worth trying.
However, the Arsenal boss also said that he wasn't sure whether sin bins would benefit the sport in the short term.
"We've got a lot going on now with decisions, with technology, with what has come in. I don't know if we're ready for that yet.
"Hopefully it's going to be tested very well before we introduce it at this level."
Meanwhile, in LaLiga, Real Madrid manager Carlo Ancelotti told a news conference on Friday that blue cards would only serve to make football unnecessarily complicated.
"The idea I have in general is to simplify the rules as much as possible," Ancelotti said.
"I don't know if [blue cards] simplify the referee's job or not. The rules are more complicated every year. I don't know if a blue card makes a referee's job more simple, or more difficult."
Sin bins have already been implemented in the lower levels of football since the 2019-20 season, where players have been shown a yellow card and been ordered to leave the pitch for 10 minutes if they show disrespect to an official. The IFAB was planning to trial blue cards to make the decision clearer to players, coaches and supporters.
The blue card trial, which was due to take place over the course of next season, will not planned to be implemented in top level competitions such as the Premier League, LaLiga, Champions League, Euro 2024 or the Copa America and it wouldn't be until the 2026-27 season at the earliest before it could have been able to enter the Laws of the Game.
"FIFA wishes to clarify that reports of the so-called 'blue card' at elite levels of football are incorrect and premature," the sport's governing body said in a statement on Thursday.
"Any such trials, if implemented, should be limited to testing in a responsible manner at lower levels, a position that FIFA intends to reiterate when this agenda item is discussed at the IFAB AGM on 1 March."
ESPN's Rob Dawson, James Olley, Alex Kirkland and Dale Johnson contributed to this report