The managers of Manchester United and Liverpool are urging their clubs' fans to stop the ugly chants at matches in the wake of the release of findings about the Hillsborough tragedy.
The rivalry between England's two most successful teams often spills over into goading in the stands, with some United fans singing songs about Hillsborough and Liverpool fans taunting their counterparts about the Munich air disaster in 1958 in which eight United players died.
Documents released on Wednesday brought the Hillsborough disaster, in which 96 Liverpool fans were killed in a crush at an FA Cup semifinal in 1989, back into public consciousness a little more than a week before United visits its fierce rival for a league match on Sept. 23.
"You would hope that maybe this is a line in the sand in terms of how the supporters behave with one another," United manager Alex Ferguson said Friday. "We are two great clubs and we should understand each others' problems in the past. Certainly the reputation of both clubs doesn't deserve it.
"The fact we are playing them after the findings we have been reading about in the last couple of days does bring a focus to it."
An independent report exonerated Liverpool fans from any blame for the Hillsborough tragedy, condemning instead police and authorities for what happened when too many fans were herded into a section of the stadium, leading to a fatal crush.
Liverpool manager Brendan Rodgers cannot understand how such an incident can be the focus of chanting.
"I speak as a human being and I don't ever like to hear anything like that, whatever club it is, that associates with other people's tragedies and death," Rodgers said. "Unfortunately you have a very small percentage of idiots at any club who will always try to smear another club's reputation.
"Of course, it is obvious these are chants that no one wants to hear about any club. Unfortunately there are that minority of supporters who will maybe disappoint but let's hope we can all move on and we can all learn from this whole process."
Before the Liverpool-United match, there is a derby match between Queens Park Rangers and Chelsea on Saturday during which fans' behaviour will be scrutinized.
It will be the first time John Terry, the Chelsea centre back, has met Anton Ferdinand in public since being acquitted of racially abusing the QPR defender at a league match last year.
The question of whether Ferdinand and Terry will shake hands as part of the traditional pre-match team ritual has overshadowed the game between the west London rivals, and could spark a reaction among fans during a match that can attract a hostile atmosphere.
Both clubs have released statements on their websites, appealing for fans to show respect at the game and warning that there will be a zero-tolerance approach to any form of discrimination or abuse.
Under the headline, "Your Behavior: A Reminder," QPR warned that "racial, homophobic or discriminatory abuse, chanting or harassment is strictly forbidden and will result in arrest and/or ejection from the ground, and in addition the club will impose a ban for one or more matches."
In Chelsea's statement, entitled "The Right Rivalry," the European champions say "fans of both clubs recognizing that abuse and discrimination have no place in a football stadium, nor anywhere else in society."