Leicester - Chelsea were forced to plead with their fans to ditch an anti-Semitic song about the club's striker Alvaro Morata after they sang the offensive chant during a 2-1 win at Leicester City on Saturday.
Morata scored his third goal for Chelsea since his club record move from Real Madrid to open the scoring.
But the adulation for the Spain star turned ugly as Chelsea's travelling fans unveiled a song aimed at their hated London rivals Tottenham Hotspur, who have traditionally attracted support from London's Jewish communities.
"Alvaro, Alvaro. He comes from Madrid, he hates the f****** Yids," sang Chelsea supporters at the King Power Stadium.
Chelsea manager Antonio Conte was asked about the song and its anti-Semitic content at the post-match press conference but head of communications and public affairs Steve Atkins quickly stepped in.
"I don't think Antonio was aware of the song so if I can just speak on behalf of the club," 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."
It is not the first time Chelsea fans have been caught making offensive chants in recent years.
Videos appeared on social media of some supporters singing anti-Semitic songs ahead of their FA Cup semi-final against Tottenham in April.
Chelsea fans also pushed a black commuter off a Metro train in Paris in February 2015 ahead of a Champions League tie.