Chelsea ordered its fans to stop singing a song about striker Alvaro Morata containing an anti-Semitic lyric that was heard during Saturday's game at Leicester.
The chant references Chelsea supporters' loathing of Tottenham and features an offensive term to describe Jewish people that they use as a derogatory alternative name for the north London club.
Morata headed in Chelsea's first goal in a 2-1 victory at Leicester.
In celebration, some Blues' supporters were reported to have sang: "Álvaro, oh, Álvaro, oh. He came from Real Madrid, he hates the f***ing Yids."
"I don't think Antonio was aware of the song," Chelsea spokesman Steve Atkins said. "The club and the players appreciate the fans' passionate support away from home, of course. But the language in that song is not acceptable at all.
"We've spoken to Alvaro after the game and he does not want to be connected to that song in any way, and both the player and the club request that the supporters stop singing that song with immediate effect."
A post-match tweet from Morata, who joined Chelsea from Real Madrid in the offseason, vaguely alluded to the outcry about the chant.
"Since I arrived, I have been able to feel your support every single day, you are amazing," the Spaniard's Twitter account read, "and I'd like to ask you to please respect everyone!"
English soccer's anti-discrimination body welcomed Chelsea's swift condemnation and called for a criminal investigation.
"There is no place for such disgusting chants at football matches and in wider society," Kick It Out said in a statement. "The organisation expects Chelsea FC to ban any supporters who are identified as indulging in such abusive conduct and expects the police to take action against any identified perpetrators."
But Gideon Falter, Chairman of Campaign Against Antisemitism, also demanded action: "Due to the repeated brazen singing of antisemitic songs by Chelsea fans, statements are no longer enough. Whilst we welcome the club's swift condemnation of this repulsive singing, Chelsea must now either identify and the punish fans who participated, or the club itself should face strict penalties from the Football Association to send a clear message to its fans."