South Yorkshire Police have made contact with Fleetwood Town and are set to talk to Joey Barton regarding an allegation of an assault on Barnsley boss Daniel Stendel.
Officers are yet to speak to the former Newcastle United midfielder but that they have approached his club with a view to doing so.
Stendel has already been spoken to, who was reportedly left needing emergency dental treatment following the incident which occurred in the tunnel at Oakwell on Saturday.
It is also believed neither manager is likely to face the media this week ahead of this weekend's League One fixtures.
Meanwhile, South Yorkshire Police have now launched an appeal for witnesses.
The 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."
The Blackpool Gazette add it is their understanding Fleetwood Town are cooperating fully with the police and the FA.
Barnsley have already confirmed they have lodged a formal complaint to the EFL and the FA following the incident.
Barton has been taking training as normal this week. Sunderland face Fleetwood in the final week of the season, their penultimate League One game this season.
Barnsley are second in League One, two points ahead of the Black Cats, who have a game in hand over their automatic promotion rivals.