Liverpool manager Brendan Rodgers has confirmed the "fight will go on" even though he admitted not hearing the chanting that ended up scarring today's tribute to the 96 victims of the Hillsborough disaster.
Aside from one chant of "Where's your Munich song" early in their side's 2-1 win at Anfield, the Manchester United fans had been on their best behaviour throughout the afternoon.
However, some time after the final whistle, when most of the Liverpool fans had left, a couple of home supporters ran across the main stand to the far corner, where the visiting contingent remained on police orders, and started making aeroplane signals.
It was an obvious reference to the Munich air disaster in 1958, in which eight United players were amongst 21 people who lost their lives.
United fans responded immediately by chanting "Always the Victims" and "Murderers" in a reminder of the Merseyside club's own recent tragedies - Hillsborough and Heysel.
Social networking sites were flooded with responses as the bitterness spilled over, even if Rodgers could shed little light on what happened.
All the Liverpool manager could say was that the battle against those who let both clubs down will go on.
"What was done at the end I cannot comment on as I didn't hear or see anything," he said.
"There is an intense rivalry here and you don't want that to end because that is all a part of what makes this the biggest game in British football.
"There is an intense rivalry here and you don't want that to end because that is all a part of what makes this the biggest game in British football." - Brendan Rodgers
"But it is on the field where competition should be and everything else, songs from Liverpool or Manchester supporters, any of us that have any human decency don't like to hear that.
"The fight will go on if there is a continuation of that but certainly at this club the work that has gone on in the last couple of weeks is something I am very proud of and the tributes today were fantastic."
Indeed, Rodgers was keen to praise the fans of both clubs, noting United supporters applauding prior to the game when a tribute of thanks was read out for the Hillsborough families whose campaign to discover the truth of what happened in Sheffield 23 years ago has now been fully vindicated.
"I think the supporters were absolutely phenomenal," he said.
"It was a significant day and the respect which was shown both teams, and with everyone shaking hands, and just moving forward is important.
"People who value human decency and humanity will have been proud today because it is important we move on from a lot of the negative stuff.
"As two massive clubs we have an obligation to society and to football to show respect because we are at the leading edge of the game.
"People will look into this today and go away with great hope."
When they entered the field prior to kick-off, both sides wore tracksuits with the number 96 on the back.
Bobby Charlton then presented Ian Rush with a bouquet of flowers before respective captains Steven Gerrard and Ryan Giggs released 96 balloons before a mosaic was unveiled which ran across three sides of the ground.
In between, Luis Suarez and Patrice Evra shook hands to end their own personal feud.
"The most important thing today was respect," said Evra.
"It was a game between two big clubs.
"There was a big tragedy. People were talking about a handshake but the stories of the clubs is bigger than that. If I hadn't shaken Suarez's hand, I would not be respecting the stories of the clubs.
"In the end I am glad this time he shook my hand. More importantly, it was important to respect the families. It was not an easy day."
United were unavailable to make an immediate comment on the post-match difficulties.
However, without being asked about them, Ferguson said he felt the day had gone well.
"Liverpool FC have done a fantastic job," he said.
"The fans were terrific. Our fans paid back that respect. I don't think anybody could have any complaints about that part.
"It was a nice touch both captains letting off the 96 balloons. It was a beautiful touch Sir Bobby giving Ian Rush the bouquet.
"It demonstrates that two great clubs can unite and do these things and then get on with the game of football with both teams trying to win.
"It was ferocious and intense. The supporters got behind their teams in the right ways which was great to know. It has been a day for football.
"Both clubs don't deserve anything else. We have to put up with some things when we've come here but Liverpool are nowhere near as bad as some other clubs with this aeroplane stuff.
"We have had to endure that for years and years. It is a sick part of society but it is only a minority from every club. They all have an element who can disgrace their club."