The issue of racism appears to have reared its head once again after a reported incident during the Blues' thrilling Capital One Cup clash at Stamford Bridge on Wednesday
A photograph appearing to show a supporter making a 'monkey' gesture in the direction of Manchester United striker Danny Welbeck has emerged on social media sites.
"We are investigating an incident involving a member of the crowd at last night's game against Manchester United," Chelsea confirmed in a statement.
"The club will be examining all available footage and asks anyone who can directly identify the individual to contact the club."
The Metropolitan Police have confirmed that they are aware of the incident, but did not comment further on the matter.
"We're aware of the incident but can't comment at this early stage," a spokesperson for the Met told Goal.com.
This latest incident follows Sunday's events, which saw Chelsea lodge a formal complaint with the FA over referee Mark Clattenburg's alleged use of 'inappropriate language', including racial words, towards midfielder John Obi Mikel. The Met Police have also began an investigation into the incident.
Last season Phillip Gannon, 58, was handed a four-year football banning order after being seen on live television making a racially offensive monkey gesture during Liverpool's clash with Manchester United at Anfield.
The incident occurred on January 28 of this year when the two sides met in an FA Cup fourth round clash, the first game between the two sides since an eight-match ban was imposed on Liverpool striker Luis Suarez, after the FA found him guilty of racially abusing Patrice Evra.
Follow James McManus on