Aaron Mokoena urged Pompey to show their character as they bid to break Fortress Forest.
The Blues captain has called on his team-mates to put problems surrounding the club out of their minds as they bid to crack the City Ground.
Steve Cotterill's men head to the east Midlands tomorrow, tasked with ending Forest's 31-game unbeaten record on their own patch in the league.
That is a run stretching back to September 2009, although the stattos aren't counting a home defeat to Blackpool in last season's play-offs.
Mokoena is gunning for his team to put last weekend's FA Cup disappointment at Brighton behind them.
He knows Pompey have picked up some impressive scalps on the road this season – including wins at high-flying Norwich and Swansea.
The 30-year-old accepts it's a tough task for his side but sees no reason why the Blues cannot stun Forest.
Mokoena said: 'I don't want to look back to last weekend.
'We've played Forest so we know who we're playing against.
'It's the second half of the season now and there will not be an easy game.
'Some teams will be defending their points and position and some need wins for promotion.
'Some are comfortable in the Championship and some want the Premier League. It's going to be tough.
'Nottingham Forest are a decent team. We saw that at Fratton Park and it will be double that when we play them away.
'We are in this position and they will be working towards what people will see as our weaknesses.
'One thing I know, though, is that we have strong characters to deal with that.'
Last weekend's FA Cup defeat at Brighton saw Pompey implode in the first half with a wave of bookings and a red card.
Boss Cotterill felt it was evidence of behind-the-scenes problems impacting on the pitch.
Mokoena is not accepting that as an excuse for the season dropping away.
He said: 'We fight among each other when we lose. Not physically but we speak about things. We know we can play better.
'It's crazy to get to a point when we are comfortable winning games and drop off. We're all in this together.
'There is no problem with the players, though.
'A big role of the manager is to stop the problems outside getting into the dressing room and that has happened. But we don't want to see that situation drifting into the dressing room now.
'We have raised our hands after Brighton and admitted we could have done better. We knew that.
'As players who have been in the game for years we could have done better in showing our professionalism.
'But come the game tomorrow we will be ready for them.'
Mokoena is now walking a disciplinary tightrope, as he stands just one booking away from a two-game ban for 10 yellow cards this season.
A suspension for him will stretch Cotterill's already paper-thin squad even further.
Mokoena has already spoken out about the need for new blood for when such scenarios arise.
The South Africa international said: 'I don't want to think about it (a suspension). I don't even want to talk about it!
'It happens and I've said we need bodies for this kind of situation. We enjoy playing. We just want to play.
'We have niggles but you want to get in there.
'The fact of the matter is the big teams out there change players. There is a reason why we do that.
'It's fresh legs. It's even more of a concern with us because of the number of games.
'Somebody has to say a thing or two.
'The gaffer has played his part and so have the players. Now we need other people to come on board.
'(Ricardo) Rocha is out with a hamstring and (Dave) Kitson is out with a red card, so there are so many things which could happen.'