Manchester United are investigating after a fan in the home section at Old Trafford was alleged to have engaged in racial abuse during Sunday's 1-1 draw with Liverpool.
The club confirmed a person was removed from the stadium and they are looking into the situation with urgency.
A United spokesperson said: "We are aware of an incident at yesterday's [Sunday] game where an individual in the home section has allegedly engaged in racial abuse.
"The individual was identified and ejected from the stadium. We are currently investigating the matter as a priority.
"Racism and all forms of discrimination are completely unacceptable and do not reflect the values of our club."
United did not comment on a potential punishment, though Liverpool will be in favour of "the strongest possible action" should someone be found guilty.
The Reds also praised United's immediacy in beginning an investigation.
A spokesperson from the Anfield club said: "Liverpool Football Club takes all allegations of this manner extremely seriously and will support the strongest possible action being taken against anyone found to be responsible.
"At this stage it would be inappropriate to comment further on the alleged incident itself other than to welcome the swiftness with which Manchester United have launched an investigation and support their stance that racism and discrimination must be treated with zero tolerance."
Manchester United players have been victim of racism themselves with Paul Pogba and Marcus Rashford being targeted by online trolls after penalty misses earlier in the season.
The Red Devils sought out meetings with both Facebook and Twitter in a bid to stop the hate directed at their players.
England's recent Euro 2020 qualifier against Bulgaria in Sofia was also marred by racism issues from supporters, which saw the match stopped twice in the first half.
UEFA opened disciplinary proceedings into the incident during the match which the Three Lions won 6-0, with the Bulgarians charged with racist behaviour, Nazi salutes and for throwing objects.
Both teams were cited for disrupting their respective national anthems during the pre-match routine.
Bulgaria's captain Ivelin Popov admitted his embarassment at the offending fans and said the game was close to being called off.
"It was important that I spoke like this because it’s a very big problem for everybody, for our federation, for England and if they said more bad words, even one more time, then maybe they would finish the game,” he was quoted by The Telegraph .
"Of course I feel embarrassed. I don’t want it to be like this, it’s not good for us, the federation and our country. How do I feel? I don’t feel good because we didn’t play well, we lost 6-0 and also what happened was terrible."