Kenny Jackett will analyse video footage of Jamal Lowe’s sending off before deciding whether to appeal.
Lowe’s challenge on Jamie Allen will warrant a suspension, the length of which has yet to be specified.
Jackett admitted his initial surprise at seeing the red card brandished by referee Lee Probert.
However, after seeing the marks on Allen’s sock, the Pompey boss acknowledged Lowe had caught his opponent high.
Jackett will now review the incident before his next move.
He said: ‘I was surprised when the red card came out.
‘I was expecting maybe a yellow but having said that I was a long way from it.
‘Lee Probert was a lot closer than me and made the call very quickly.
‘Looking at Jamie Allen’s sock when he came off, it quite clearly has caught him high. I wouldn’t think it was deliberate, it didn’t look deliberate.
‘But I can’t deny he did catch him high and we have to accept it.
‘It was a forward’s tackle and it’s a shame for Jamal.
‘He came on where we needed that width and could pin the left-back a little bit. He’s had a good pre-season and shown some promise.’