Charlton boss Karl Robinson will discipline his players after images of their Christmas party appeared in social media within hours of their defeat against Pompey.
The Blues won the game at The Valley 1-0, thanks to a 47th-minute own goal by Josh Magennis.
The victory saw Kenny Jackett's side close the gap on the sixth-placed Addicks to three points, with Pompey currently sitting just outside the play-off places.
Saturday's match also marked the 25th anniversary of Charlton's return to The Valley, with the players extending the party atmosphere generated when they headed straight to Newcastle for a night out.
Robinson, who criticised Jackett after the game for comment made in his post-match interview, had no problem with the pre-arranged Christmas party.
But he was unhappy that Lewis Page and Leon Best uploaded video footage of the event, plus images that appeared on Instagram of players singing on the train.
'People will feel hurt by that and feel that it is disrespectful.' said the Charlton manager..
'I will deal with it. There is a big difference between going up there and flaunting it.
'You can have a good time without social media. You’ve got to go out and keep that to yourself.'