Steve Cotterill has admitted Pompey's off-the-field concerns are now affecting his players.
The Blues have picked up only two points from their past four league games.
On Saturday, they were dumped out of the FA Cup by Brighton.
Amid it all, Cotterill's squad is shrinking by the match.
The Pompey boss has been forced to name just four substitutes in two of the past three fixtures as injuries and suspensions pile up in his threadbare squad.
On top of that, he has been handed a small transfer kitty to address the problem.
Cotterill's players looked demoralised and frustrated during their woeful 3-1 Withdean Stadium defeat, collecting seven bookings and a red card in the process.
It was an ill-disciplined display, much to the disappointment of the away following. And Cotterill conceded events off the pitch are now starting to impact on his team.
He said: 'I think a little bit of what has been going on off the pitch has been affecting the players, probably over the past couple of weeks.
'There is a little bit of frustration in them.
'As manager, I'm trying my best with it, really, to remain positive.
'Anybody who knows me anyway knows I am a positive person.
'I stay upbeat in the toughest times because you've got to.
'Like I say to the lads, when you reach deep down into the pit of your gut, sometimes you will find strength even you never knew you had.
'And I think we've got to do that because that's where we are.
'There have been some dents we've had to take and we've got to carry on getting through them because we've got to.'
Cotterill and his players are not ready to throw in the towel, though.
Less than a month ago, the play-offs were the aim following an impressive victory at Norwich.
Since then, Pompey have slipped down the Championship table as their squad problems have deepened.
Michael Brown and Richard Hughes are unlikely to play for the club again after having contract offers withdrawn.
The loss of Brown, who had played every match this season before he was forced to sit out over a clause in his contract, has clearly been felt in the subsequent performances.
In addition, ahead of Saturday's trip to Nottingham Forest, there are injury concerns over Ricardo Rocha and Liam Lawrence, while Greg Halford and Dave Kitson are suspended.
But Cotterill has vowed not to wave the white flag.
He added: 'We've got some great fans who give their all to the club and we certainly can't give in.
'We just need a few more to go with those players.
'When they are tired and on their heels a little bit, you just want to call on a couple more.'