A video has emerged of a West Ham United supporter racially abusing Tottenham Hotspur's South Korean striker Son Heung-min.
In a clip posted on Twitter, Son is asked by a man if he "does DVDs" - a joke based on the racist stereotype of Koreans selling pirate copies of movies door to door.
The former Bayer Leverkusen man attempts to laugh off the comment before winding up his car window, but not before the abuser shouts "Yeah, I'm West Ham you w****r!"
The actions of the person in question - who identifies himself as a Hammers fan - has been condemned by both rival clubs.
A Tottenham statement read:
Racist behaviour is completely unacceptable and we hope that the individual is identified to the authorities and the necessary action taken.
A West Ham United spokesperson added:
West Ham United have a zero-tolerance approach to any form of discrimination and unreservedly condemn the actions of the individual in this video.
Anyone behaving in this manner is not representative of our club and its values, and anybody who witnesses discrimination or abuse such as this at West Ham are urged to contact us in confidence at firstname.lastname@example.org.
This is not the first shameful act to involve Tottenham and West Ham this season.
Last month, a Tottenham fan threw a cup of urine into the Hammers section during their Carabao Cup match at Wembley Stadium.