Anzhi Makhachkala have urged Lokomotiv Moscow to identify and punish the supporter who racially abused defender Christopher Samba yesterday afternoon.
The Congolese centre-back had a banana thrown at him during the match by a so-far unidentified fan.
His club Anzhi have described the incident as "idiotic" and are calling for a suitable penalty to be handed out to the offender.
"We are deeply disappointed with the idiotic episode that happened to our player Christopher Samba after the match Lokomotiv vs. Anzhi," read a statement from the Russian club.
"We are assured that the representatives of the football authorities and [the] security service of Lokomotiv will settle this issue and the guilty will be identified and punished."
Samba joined Anzhi from Blackburn Rovers last month.