The Football Association will investigate claims that Manchester United's Patrice Evra was racially abused by Liverpool's Luis Suarez.
Evra says the incident occurred in Saturday's 1-1 draw between the teams.
A Liverpool spokesman told the Press Association that Suarez "categorically denied" the allegation.
An FA statement read: "Referee Andre Marriner was made aware of an allegation at the end of the fixture and has reported this to the FA."
It added: "The FA will now begin making enquiries into the matter."
Evra was quoted as telling French TV station Canal Plus: "There are cameras, you can see him [Suarez] say a certain word to me at least 10 times."
The game at Anfield ended 1-1 after Liverpool captain Steven Gerrard's free-kick was cancelled out by Javier Hernandez's late header for United.