Both Pep Guardiola and Jurgen Klopp urged supporters to behave ahead of Manchester City's trip to Liverpool.
Pep Guardiola has called on Merseyside police to ensure there is no repeat of the 2018 attack on Manchester City's bus when they face off with Liverpool at Anfield on Sunday.
City's bus was damaged when making its way to the ground for the first leg of a Champions League quarter-final tie against the Reds, which Liverpool won 3-0.
This week, a poster circulated on social media in which fans were encouraged to "greet" City's coach ahead of the top-of-the-table Premier League clash.
And Guardiola urged police to make sure his team arrive without incident.
"No. Hopefully it will not happen again, so the police knew about [it] for the Champions League game before and didn't do anything," he said.
"I don't know what they are going to do, hopefully it will be an incredible game at Anfield for the Premier League and for all around the world.
"That is what we want. Hopefully it's not going to happen, the same that happened two seasons ago when we arrive, which was more than one bottle."
Reds boss Jurgen Klopp issued a similar message, calling on fans to provide vociferous vocal backing in the stands but not to engage in "senseless" acts.
"I'm a big believer of fan power – in the stadium. That's completely different. [The coach incident] was a senseless thing," Klopp said.
"If somebody at Man City is concerned still, then it's our fault. Not that we did it all together, we all didn't throw the bottle or whatever it was, but it was one of us. That's why we are responsible.
"All of us have to make sure that something like this will never happen again. It's long ago and since then nothing has happened. I don't think it was Man City specific.
"After the punishment we got, we haven't had a similar situation – the positive outcome of something like this.
"Actually, we used to enjoy that [the coach welcome], when we come in, it's impressive. It's a nice part of football, but if you overstep the line then it's not allowed that you do it anymore.
"That's how it is. I wish I could say it will never happen again but unfortunately I can't. But what I can say is we will do everything that it will never happen again.
"Everybody agrees to feel this responsibility that it won't happen again. That's why I say – go in the stadium, nothing to do outside, have your food, go in, wait for the team, we will come, let's make a pretty special game of it."
Superintendent Paul White issued a statement on Merseyside Police's official website addressing the poster doing the rounds on social media and insisted they are doing all they can to ensure there are no major incidents.
"As with any match, a comprehensive and appropriate policing operation has been put in place ahead of Sunday's game and we have liaised with both clubs and their supporter groups," he said.
"We are aware of one poster on social media regarding a bus welcome. The corresponding last fixture ran smoothly and we are working to ensure this game can be enjoyed safely by all as well as minimising any disruption to local residents and roads.
"As with all Premier League fixtures at Anfield, we will have officers on duty at the ground, both uniformed and plain clothed, supported by mobile CCTV, provided by Liverpool City Council, and specialist resources including the Dog Section, mounted police and the National Police Air Service. We will also have a city centre policing plan in place throughout the day. This is standard procedure.
"We know that this will be a busy operation and we hope that fans attending the match will act as ambassadors for their clubs.
"As usual we would ask fans with tickets to arrive at the ground as early as possible. Fans without tickets should not attend at all; they will not be allowed entry into the stadium."