Prior to kick-off, there had already been a furore surrounding the fixture due to United captain Patrice Evra’s return to Anfield for the first time since Luis Suarez was handed an eight-game suspension for racially abusing the Frenchman in October.
Whilst Evra was jeered by sections of the crowd, the game passed largely without incident, as Dirk Kuyt’s late strike ensured Kenny Dalglish’s side progressed to the fifth round of the Cup.
However, Merseyside Police have since confirmed to Goal.com that an alleged incident of racism from a supporter is “under consideration for investigation”, after an image appeared on twitter.
Match Commander, Chief Superintendent Jon Ward said in a statement: "We can confirm that specialist officers are reviewing match footage, as a result of a picture posted on Twitter.
"This matter is now under investigation by specialist hate crime detectives and we are working with Liverpool Football Club to identify the man in question.
"We take all forms offensive behaviour seriously, and we will always thoroughly investigate such claims. We cannot allow this type of behaviour to affect the enjoyment of genuine fans.
"We will continue with our efforts to deal with the small number of individuals who commit offences at football matches, in particular, with the continued use of football-banning orders."
The allegation comes as the Reds cap off a fine week on the domestic Cup front, having reached the League Cup final on Wednesday at the expense of Manchester City.
The Police were also quick to stress that this was an isolated incident, with the vast majority of both Liverpool and United fans well-behaved throughout the clash.
Ward added: "I would like to thank the majority of fans for their behaviour and co-operation during today's Liverpool Vs Manchester United Match at Anfield.
"We knew this would be a busy operation and most fans can be proud that they acted as ambassadors for their cities and their clubs.
"Despite the large numbers of supporters from both clubs and lively atmosphere only 17 people were ejected from the ground and at this time, two people arrested during the policing operation, all for low level incidents.
"We continue to work with partners and hope fans have a safe journey home.
"As a matter of course, Merseyside Police monitors Twitter, other social networks and match footage during high-profile events such as today's match."
Earlier this month, a Liverpool fan was arrested for making racially motivated comments towards Oldham Athletic’s 20-year-old full back Tom Adeyemi during the two sides’ third-round FA Cup clash, with the youngster making a full statement to the Police.
Saturday’s incident follows on from the FA’s decision to cancel the pre-game handshake between QPR and Chelsea at Loftus Road, with concerns that Anton Ferdinand may snub John Terry over the race row surrounding the pair, and in turn provoke ill-feeling amongst the crowd.
Officers have released a still of a man who may be able to assist officers, in connection with this alleged incident. Anyone who recognises this man or who has any information about this incident is asked to contact 0151 777 4067 or Crimestoppers anonymously on 0800 555 111.