Chelsea have urged their fans to 'support the team in the right way' ahead of their Premier League clash with rivals Tottenham on Wednesday night.
Supporters from both sides will be heavily scrutinised over the use of the 'Y-word' as the London duo meet at Stamford Bridge for what could be a make-or-break game for Maurizio Sarri.
Chelsea have issued a lengthy statement on the day of the game to warn their fans about potential ramifications for those who use the derogatory term.
The club said: 'The team enjoyed fantastic support at our home match against Tottenham in the Carabao Cup semi-final second leg last month, with the brilliant atmosphere at the Bridge driving the players to success on a dramatic night, and we would like to once again thank our fans and remind supporters to keep support positive.
'A small minority of Chelsea supporters have in the past tarnished this derby by using antisemitic chanting, noises and gestures, including the Y-word, offering the justification of opposition fans using those terms as a form of identity.
'We have repeatedly made our stance on this clear – there is no place for such behaviour at Chelsea Football Club.
'Such actions or language have no place anywhere in football or society and everybody at Chelsea is proud to be part of a diverse club. Our players, staff, fans and visitors come from a wide range of backgrounds, including the Jewish community, and we want to ensure everyone feels safe, valued and included.
'We urge everybody to show their support in the right way and do their bit to help the Blues claim an important and memorable victory as we aim to pick up vital Premier League points.'
The club statement comes after chairman Bruce Buck criticised Tottenham fans for using the Y-word themselves.
London's Metropolitan Police backed down from their initial claims that they would arrest Tottenham fans for using the Y-word in 2014 but rival fans could be detained.
'There is a particular problem with the Y-word,' Buck said. 'We think the use of the Y-word by Spurs supporters, or by anybody, is wrong. It's very confusing... because UEFA thinks it's wrong and are charging our fans. ... We're trying to say there shouldn't be a ban.
'There's a particular problem for the police in that if you've got the 3,000 Spurs fans chanting it how do you drag 3,000 people out of the stadium? I respect that.
'They can say they're just not going to arrest and prosecute because it's too difficult or whatever, but they shouldn't be saying it's OK to say that.'
Fans have been urged to contact Kick It Out to report any kind of discriminatory or antisocial behaviour.