Preston manager Paul Heckingbottom has labelled Milutin Osmajic's lack of discipline as 'totally unacceptable', with the forward facing another ban after headbutting Hull's John Lundstram on Tuesday night.
Osmajic headbutted Lundstram in stoppage time at Deepdale, as Preston trailed Hull City 3-0 in the Championship.
The forward was initially seeing pushing Lundstram away, leading to players from both sides and referee Stephen Martin running over to the pair.
Osmajic was then seen headbutting Lundstram directly in front of the referee, with the official quick to reach for his pocket and show him a red card after leading him away from a crowd of players.
He was seen initially smiling following the dismissal, before raising his shirt to cover his face as he made his way off the field.
Osmajic is expected to receive an automatic three-match ban for violent conduct for the incident, which contributed to a melee leading to one member of staff from each side being sent off.
This would mean Osmajic would have been suspended for 20 matches across the last two seasons.
Osmajic was banned for eight matches last season for Owen Beck's neck in a game against Blackburn.
He was then hit with a nine match suspension back in November, after being found guilty of racially abusing Burnley's Hannibal Mejbri in a Championship match last year.
Osmajic had denied the allegation, but a Regulatory Commission found the charge to be proven, leading to the ban, a £21,000 fine and mandatory education course.
Preston stated at the time that the club was 'extremely disappointed' by the decision and vowed to support Osmajic.
Speaking after Osmajic's red card on Tuesday - which came four matches after he returned from his previous ban - Preston boss Heckingbottom admitted he felt let down by the 26-year-old Montenegrin international and criticised his lack of professionalism.
'Yeah it is a sending off, Steve has got no choice,' Heckingbottom told BBC Radio Lancashire.
'Yeah he has [let us down], he has not cost us the game but we have got three big games coming up and we are a striker down.
'A lack of discipline is totally unacceptable. In my time here if he gets three games for that, it will have been 20 games missed.
'They are different issues, don't get me wrong, but a sending off for a tackle or something to help the team is a lot different.'
'He has not learned his lesson. The issues are totally unconnected in terms of football aren't they.
'In terms of other things, the word professional, we are professional people and footballers, there is a way to act.
'Whether that's a tackle on the pitch, discipline away from it, training ground, there is a way to be professional.'
Osmajic has scored 28 goals in 96 matches for Preston since joining the club in 2023, including five goals in 15 Championship games so far this season.
He is now set to miss their upcoming matches against promotion chasers Middlesbrough and Ipswich, who are third and second respectively in the table, and a match against Portsmouth.
Preston are in the Championship play-off spots in sixth place, but suffered a blow with the 3-0 home defeat by Hull.
Liam Millar, Akin Famewo and Oli McBurnie scored for Hull on Tuesday, with the Tigers rising to fourth in the table.