Police have appealed for fans who may have filmed an alleged confrontation between Fleetwood boss Joey Barton and Barnsley counterpart Daniel Stendel to come forward.
South Yorkshire Police launched an investigation into an alleged incident in the players' tunnel after the Tykes' 4-2 Sky Bet League One victory over Barton's side on Saturday.
Now they are calling for witnesses who may have captured what happened on mobile phones to assist.
A South Yorkshire Police statement said: "Police investigating reports of an assault at Barnsley Football Club on Saturday 13 April are appealing for witnesses as enquiries continue.
"The incident is believed to have taken place in the tunnel around 5pm, following the conclusion of Barnsley's match against Fleetwood Town, and left one man with facial injuries.
"At this time, no arrests have been made in connection with the incident.
"Were you at the game on Saturday with a view, or in the area, of the tunnel? Did you see what happened?
"Officers are particularly keen to speak to anyone who may have caught the incident on camera or who may have any mobile phone footage immediately before or after the incident occurred.
"If you think you can help, please call 101 quoting incident number 326 of 13 April 2019."