Joey Barton was physically stopped by police as he tried to leave Barnsley's ground after he allegedly assaulted their manager Daniel Stendel.
Barnsley striker Cauley Woodrow tweeted that Fleetwood manager Barton confronted Stendel following the game, which ended in a 4-2 victory for the home team.
The tweet has since been deleted. A South Yorkshire Police spokesman said: "We are aware of something that has taken place in the tunnel after the game and we are investigating."
Woodrow, who scored in his side's victory, claimed Stendel was left with "blood pouring from his face".
Neither club fulfilled their post-match media duties after the game, which saw Fleetwood have Harry Souttar sent off after 65 minutes with Barnsley leading 2-1.
Manchester City's Bernardo Corradi celebrates scoring the opening goal of the game with Joey Barton
Manchester City's Joey Barton celebrates scoring the opening goal of the game
Manchester City's Darius Vassell celebrates scoring the opening goal of the game with Claudio Reyna and Joey Barton
Newcastle United footballer Joey Barton leaves Liverpool Magistrates Court where he answered assault and affray charges.
ALTERNATIVE CROP. Premiership footballer Joey Barton, 25, is released from Strangeways Prison in Manchester.
Premiership footballer Joey Barton, 25, is released from Strangeways Prison in Manchester.
Newcastle United's Joey Barton (centre) celebrates with his team mates after scoring the first goal of the game from the penalty spot.
Chelsea's Fernando Torres and Newcastle United's Joey Barton (left) get into an altercation
File photo dated 13/08/2011 of Referee Peter Walton has a word with Newcastle United's Joey Barton (on floor) as he is helped up by Arsenal's Andrey Arshavin.
Tempers flare after Queens Park Rangers' Joey Barton clashes with Manchester City's Sergio Aguero
Queens Park Rangers' managing director Philip Beard embraces Joey Barton after the match
tempers flare between West Bromwich Albion's Diomansy Kamara (no15) and Ronnie Wallwork (r) and Manchester City's Joey Barton (2nd from r) and Ben Thatcher (l)
Liverpool's Daniel Agger grimaces in pain after being fouled by Manchester City's Joey Barton
Manchester City player Joey Barton responds to fans taunts at the final whistle
England's Joey Barton replaces Frank Lampard
Manchester City's Joey Barton protests with Referee Mike Dean
Newcastle United footballer Joey Barton leaves Trafford Magistrates' Court, Manchester, after pleading not guilty to attacking a team-mate in a training ground bust-up.
Newcastle United's Joey Barton (l) challenges Manchester City's Shaun Wright-Phillips (r) for the ball
Liverpool fans shout at Newcastle United's Joey Barton after he fouled Liverpool's Xabi Alonso (not in picture).
Newcastle United fans celebrate winning the Championship title at the end of the game on the pitch with Joey Barton
QPR's Joey Barton clashes is sent off during the Barclays Premier League match at the Etihad Stadium, Manchester.
Footballer Joey Barton (centre right) and Alastair Campbell head off on a 5k run at the start of the second day of the Conservative Party Conference at Manchester Central in Manchester.
Robbie savage and Joey Barton watch during the RBS Six Nations match at Twickenham, London.
Paris Saint Germain's David Beckham and Olympique Marseille's Joey Barton (right) in action during the Coupe de France match at Parc des Princes, Paris, France.
Queens Park Rangers' Clint Hill (centre right) and Joey Barton (centre left) lift the Sky Bet Championship play-off final trophy on the gantry after victory over Derby County
Queens Park Rangers' Joey Barton and chairman Tony Fernandes celebrate victory on the Wembley turf.
Burnley's Joey Barton signs autographs as he arrives at Hillsborough
New Rangers signing Joey Barton during a photocall at Murray Park training ground, Glasgow.
Rangers' Joey Barton reacts during the Ladbrokes Scottish Premiership match at Celtic Park, Glasgow.
New Fleetwood Town manager Joey Barton holds up a scarf after the press conference at Highbury Stadium, Fleetwood.
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Barnsley said in a statement: "The club can confirm there was an alleged incident in the tunnel area that took place following the conclusion of today's match, which South Yorkshire police are currently investigating.
"The club is assisting the police with its enquiries and, as a result, we are not in a position to make any further comment at this time."