Pompey could be slapped with a £5,000 to £10,000 fine following last night’s actions by a supporter.
The fan left the Fratton end to kick the ball amid supporter frustration over York City goalkeeper Scott Flinders wasting time by delaying taking goal-kicks.
He was subsequently escorted out of the ground by stewards and faces a lengthy club ban.
As for Pompey, they await the Football Association’s verdict to discover whether they will be punished.
It is the second Fratton Park incident in recent weeks, with a Macclesfield supporter entering the pitch area from the Milton end during the non-league side’s 2-1 FA Cup defeat.
Chief executive Mark Catlin said: ‘Everyone was sharing the frustration of the goalkeeper and the time it was taking to take goal-kicks.
‘However a supporter, for whatever intention, coming on to the field of play is a criminal offence.
‘The fact a Macclesfield fan also recently came onto the pitch is also taken into account. It does not matter who the person follows, we have obligations.
‘The punishment figure can vary, there is no standard fine, but it is in the region of £5,000 to £10,000.’