Sir Alex Ferguson has pleaded for Manchester United and Liverpool fans not to cause trouble at Old Trafford this afternoon.
Fears the bitter rivalry between the north-west giants could spill over have been expressed in recent days, with both sides mindful of the bad blood which exists between the two sets of supporters.
United were forced into an expensive clean-up operation following Liverpool's last visit for the FA Cup semi-final against Chelsea in April when toilets were wrecked.
Trouble then erupted outside the ground, which some claimed was sparked by the excessive celebrations of United skipper Gary Neville following his side's last-gasp win.
Since then, the ambulance carrying stricken United star Alan Smith away from Anfield was attacked by thugs, leading to even greater concern that home supporters may seek to exact revenge this weekend.
United have attempted to soothe tensions by erecting posters commemorating Liverpool's illustrious history inside the visiting section, part of a series of measures which also include an on-pitch tribute to Sir Bobby Charlton by Reds legends Roger Hunt, Ian Callaghan and Tommy Smith.
Representatives of both clubs are crossing their fingers that the initiative pays off, with Ferguson claiming fans run the very real risk of eventually forcing the fixture to be played behind closed doors should the violence persist.
"Over the last few years there have been some experiences of fan behaviour which we do not want to see again," Ferguson said.
"Both sets of supporters should realise they are supporting two great clubs and imagine what it would be like if there wasn't a United-Liverpool game, or it was played with no-one being able to attend it.
"This is not just an important fixture, it is a platform for everyone in the country to see. We just have to keep a lid on things because we don't want the situation to get out of hand."
He still regards the fixtures with the Merseyside giants as the biggest of the season, even though Arsenal, then Chelsea, have been the greater barrier to success more recently at Old Trafford.
While battles with Arsenal in particular have tended to bring out all that is bad within the two sets of players, Liverpool games are usually at least played with the right spirit, even allowing for Neville's wild celebrations which earned the England defender a £5,000 fine both he and his manager still believe to be unjust.