Sheffield United have vowed to ban a supporter who lit a flare during the club's clash away at Port Vale on Friday.
The Blades ran out 3-0 winners at Vale Park but the match was marred by crowd trouble before the start of the game.
However, the club say they are intent on tracking down a supporter who was part of the away following that day.
The supporter was pictured lighting a flare during the match and Sheffield United said, once identified, he will be banned from Bramall Lane.
United's Safety Officer, Jurgen Morton-Hall comments: "Each EFL club is responsible for the actions of its own supporters - home or away - and the actions of a minority is putting the lives of fellow supporters in danger as well as potentially putting the club at risk of costly and severe sanctions from The Football Association.
"In addition, topically, actions of our fans could impact on ticket allocations for certain matches."
Sheffield United have reminded supporters that there is a "strict zero-tolerance policy" towards fireworks, flares, smoke bombs and anti-social behaviour.
Fans who are caught breaking these rules risk prosecution and banning orders.
The Blades travel to MK Dons on Saturday and fans have been informed that a thorough search regime will be in place on entry to Stadium MK.
Pyrotechnic-detention dogs will be on duty and anyone found in possession of a device or other prohibited item will be denied entry to the stadium, or removed from it, and is likely to be arrested by police.
A Sheffield United statement read: "It is a criminal offence to take fireworks, flares or smoke bombs into Bramall Lane and all EFL grounds.
"Such items will be confiscated immediately and United have measures in place to identify perpetrators."