Mason Holgate's accusations of alleged racist language being used by Liverpool forward Roberto Firmino will be investigated by the Football Association (FA).
Referee Bobby Madley passed on the allegation in his report after Friday night's FA Cup third round match, in which Firmino and the Everton defender were involved in an altercation.
Holgate pushed the Brazilian, who was shielding the ball over the sideline, into the crowd before the Liverpool forward reacted angrily.
No action was taken by Madley at the time, but he did pass a message on to the fourth official and the suggestion of racist abuse was flagged by the official to the FA.
"[The referee] was made aware of an allegation during the game at Anfield last night and has subsequently reported this to the FA, which will now begin making enquiries into the matter," a statement said on Saturday.
Everton boss Sam Allardyce and Reds manager Jurgen Klopp refused to be drawn on the incident after the match, which was won by a late Virgil van Dijk goal.
A Liverpool spokesperson said: "The club and player will fully co-operate with the relevant authorities to ensure the facts are established in a thorough manner if deemed necessary or requested.
"While that process is ongoing we will not be making any further comment."
The team's respective managers were not drawn on the incident, with Allardyce saying he had left it in the hands of director of football Steve Walsh.
Allardyce said: "I'm telling you nothing until whatever systems are used to find out exactly what happened and what didn't happen.
"I'm here to talk about football, not about controversial incidents. I only want to talk about football. Anything else outside of that that happens has to be dealt with by the authorities."
Klopp was also unwilling to reveal what happened between the pair, saying he initially thought Holgate had committed a foul.
"I only heard about something but I can't say anything about it because so far I couldn't speak to anybody," the German said. "I think from now on, first of all the club will answer. It's like this, I don't really know anything about it.
"I misjudged the situation obviously completely because I thought it was about the Holgate foul. At the end, there was no foul, no yellow card, nothing. I didn't get it to be honest.
"It was a throw in so I didn't understand the whole situation after the game and I got information that something happened, but I can't say anything about it."