The two teams met for the second time in four days, with Chelsea emerging 5-4 victors this time in a spirited match that went to extra time.

This morning though a photograph has surfaced which appears to show a Chelsea fan making a monkey gesture, with Man Utd’s Danny Welbeck also in the shot, although it is unclear if the gesture is aimed at him.

“Chelsea Football Club can confirm we are investigating an incident involving a member of the crowd at last night’s game against Manchester United,” Chelsea FC have said in a statement.

“The club will be examining all available footage and asks anyone who can identify the individual to contact the club.

“Chelsea FC is committed to removing all forms of discrimination and if we have sufficient evidence we will take the strongest possible action, including supporting criminal prosecution.”

Photo: Getty.