Barnsley have confirmed they have made an official complaint to the English Football League after manager Daniel Stendel was allegedly assaulted by Fleetwood boss Joey Barton.
Stendel and Barton clashed in the tunnel following the clubs' League One match on Saturday afternoon.
A club statement read: 'Barnsley can confirm that it has lodged a formal complaint to both the English Football League and the Football Association. This is following an alleged incident at the conclusion of the match on Saturday 13th April between Joey Barton and Daniel Stendel.
'The club is also currently working with the police and assisting with all enquiries regarding the incident. No further comment will be issued while police investigations are ongoing.'
Police have already spoken to Stendel. Sportsmail understands that the German met officers at Oakwell on Monday, and discussions are said to have lasted for more than an hour.
Stendel, 45, underwent emergency dental work after claims he was barged from behind by Barton in the tunnel at the end of Saturday's clash.
Insiders have said Stendel subsequently banged head first into a metal support at the side of the tunnel, damaging two front teeth. The FA have now received the referee's report and that it does make reference to the alleged tunnel fracas.
Barton was caught up in more controversy when a woman police officer prevented his car, driven by Fleetwood chief executive Steve Curwood, from leaving the ground. The car was allowed to continue after a two-minute stand-off.
The 37-year-old was not interviewed immediately by police, who had not questioned the Fleetwood manager by Sunday afternoon.
A spokesman for South Yorkshire Police said: 'South Yorkshire Police is continuing to investigate reports of an assault at Barnsley Football Club on the afternoon of Saturday April 13. No arrests have been made at this time and enquiries remain ongoing.'
It could spell trouble for Barton, who took over at Fleetwood after serving 13 months of an 18-month ban from football for gambling breaches.
It is understood the incident occurred with the majority of players still out on the pitch following full-time. The atmosphere inside Barnsley's tunnel was described as 'volatile' after the alleged assault.
Barnsley striker Cauley Woodrow tweeted after the match: 'Firstly @ftfc to have a manager that can physically assault another manager in the tunnel is disgusting, causing our manager to have blood pouring from his face! People like you don't deserve a place in the game of football.'