Several players appeared to be involved in an incident in the tunnel after Manchester United's 3-1 victory at Middlesbrough.
A fiery finish to the Premier League meeting at the Riverside Stadium ended with Eric Bailly and Ashley Young being held back from an apparent confrontation by security staff.
Marouane Fellaini, Jesse Lingard and Antonio Valencia’s goals had earned Jose Mourinho's side three points, with Rudy Gestede’s late strike briefly offering the hosts hope of a comeback.
Shortly after pulling the score back to 2-1 in the 77th minute, Gestede clashed with Bailly, holding the defender around the neck. Both players had to be pulled apart by their team-mates.
After the final whistle, tempers flared again, with television cameras showing several United players congregated in the mouth of tunnel. Bailly and Young look to move down the tunnel, only to be prevented from doing so by Middlesbrough stewards, officials and their own teammates.
— UtdHQ (@UtdHQ) March 19, 2017
When questioned on what had happened at full-time, United’s opening goalscorer Fellaini simply said: “Nothing.”
Steve Agnew, the Middlesbrough caretaker manager, also denied all knowledge of the incident, telling BT Sport: “I didn't see that. I was inside quickly, so I didn't see that.”