Sheffield United's Keith Gillespie has admitted a charge of violent conduct after being sent off during his side's 3-1 defeat by Reading at the weekend.
Gillespie joined Sheff Utd in August 2005 from Leicester
The Northern Ireland winger was dismissed just 12 seconds after coming on as a substitute after lashing out at Reading midfielder Stephen Hunt.
The Football Association fast-tracked the charge, and Gillespie is facing up to two months out through suspension.
The disciplinary hearing is scheduled for 30 January.
In the incident against Reading, Gillespie was sent off by referee Mark Halsey for elbowing Hunt within seconds of arriving on the pitch.
Gillespie, who already faces a three-game ban for his red card, then appeared to hit Hunt in the face on his way off the pitch.
But he could be handed an additional three-game ban if he is found guilty by the FA's disciplinary panel, with the incident regarded as "outside jurisdiction".
The FA is still considering other matters from the same game involving the touchline row between Blades manager Neil Warnock and Royals coach Wally Downes.
Gillespie moved to Bramall Lane on a free transfer from Leicester in August 2005 and has also played for Manchester United, Wigan, Newcastle and Blackburn.
He had handed in a transfer request recently but any move now appears unlikely because of the potential suspension.