Michael Appleton issued a disciplinary warning to his troops and promised he won’t accept silly suspensions.
The Blues boss has told his players he won’t stand for cheap bookings.
Pompey go into the Christmas period with a string of players walking a disciplinary tightrope.
Luke Varney, Greg Halford, Tal Ben Haim, David Norris and Joel Ward are all one card away from a suspension, ahead of the Boxing Day clash with Millwall.
The amnesty on cautions arrives after the meeting with Leicester on New Year’s Eve, meaning those players have to avoid bookings until then, if they are to stay in contention.
Appleton knows he can ill-afford to lose players from his squad and has made that clear to his men.
He said: ‘I’m a big believer in discipline and I’m sure everyone is aware of that.
‘When I walked in we had four or five players on four yellow cards. That’s still the case now.
‘The cut-off point is January 1, so the Leicester game is the last one.
‘It’s going to be difficult because we’ve had to do it for four or five games already.
‘The likelihood is that someone is going to get suspended.
‘They have been disciplined enough so far and referees have been quite sensible, so hopefully we get another sensible one on Boxing Day.
‘It’s a volatile atmosphere there and the fans can make it difficult. Millwall are very competitive.
‘We have to avoid a few of them getting a yellow card before the Leicester game.
‘If they do, it will probably be a miracle so I have to prepare myself, however disciplined they have been – and they have been fantastic.
‘I can’t speak highly enough of them – but there’s always a chance that one of them might pick one up.’
Appleton believes the only acceptable cautions are those picked up in stopping the opposition.
He stated any cards for dissent or getting involved in scraps with other teams will be punished.
Appleton said: ‘I won’t accept yellow cards for anything other than a tackle.
‘I’ve been telling them non stop, relaying back to them how important it is to have 11 players on the field.
‘I’ve tried to improve the discipline off the field as well.
‘I’m a big believer that if you’re professional and organised off the field you tend to bring good habits on to the pitch.
‘I’ll never stop someone making a tackle but it’s the silly ones like arguing with the referee or getting involved with players that, for me, is a show.
‘The important ones are making last-ditch tackles and you have to make it.
‘I’m trying to instil that I will be on top of them if anyone steps out of line.
‘I remind them all the time the importance of having good discipline.’