Detectives want to trace five men over disorder at a Sheffield Wednesday away game.
Trouble broke out when the Owls played Derby County at Pride Park on Saturday, October 21.
CCTV images have been released of men believed to hold vital information about the incident.
The men themselves or anyone who recognises them should call PC Roger Brown of Derbyshire Police's Football Unit on 101.
Information can also be passed on via Crimestoppers on 0800 555 111.