Steve Cotterill has called on his flagging troops to deliver one final push to see out the campaign after wilting at Cardiff.
The Pompey boss admitted he felt some of his men had one eye on the summer after they fell to a 3-0 loss against the Bluebirds.
The first-half dismissal of Ricardo Rocha proved the key moment in the defeat against the promotion chasers.
But Cotterill feels the labours of a tumultuous campaign are now weighing heavily on his men.
He wants to see them dig deep over the final four games of the campaign.
Cotterill said: ‘We looked like we were running on empty. Since we got those points to stay up we have used so much energy.
‘There has been a lot of stress at Portsmouth Football Club this season.
‘I think it looks like some of our boys are already packing their cases and going on their summer holidays, if you know what I mean.
‘If everyone gave the effort Hermann gave and people like Joel Ward, Jonathan Hogg and Liam Lawrence we’d have been okay.
‘If we had the energy that those four performed with we could have got something out of the game.
‘Our boys have given so much energy this season.
‘There are tired legs and tired minds there.
‘But now we’ve got four games left and then maybe we can close the book on this rehabilitative season.’
Rocha’s red card proved controversial after he was dismissed for a head-to-head tussle with striker Jay Bothroyd.
The defender left the pitch with blood streaming down his face but there was no action taken against Bothroyd.
Cotterill feels his men can ill afford to let a mentality that they are being hard done by set in – even if it appears it’s the case.
He said: ‘It looks like we need something to go right for us in a game. When it goes wrong it seems like a catastrophe when it isn’t.
‘We have to rid ourselves of that.
‘Then they go down to 10 men and they think: “Here we go again”.
‘We didn’t have enough in our 10 men to get a result.
‘It might have been fair if they both got sent off and maybe we wouldn’t have lost so much heart.
‘It’s tough on them. They’ve put an unbelievable amount of energy into this season.
‘They just look as if they are on their last legs now.
‘We still have a couple of big games to play, so we have to rest up and then get working again.’