Paul Cook warned big improvements are needed to get Pompey firing again.
And the Blues boss refused to blame the referee for his side failing to deliver victory against Accrington Stanley.
Pompey came up short of the levels expected at Fratton Park in Saturday’s 0-0 draw.
That meant they missed out on the chance to move into the automatic promotion spots in League Two.
Cook wasn’t pleased with the level of performance from his side and knows a repeat against Barnet will see more frustration.
He said: ‘We have to be better than that.
‘We have to be better against them than we were against Accrington.
‘We’ll get a good week’s training into the players before Barnet.
‘It’s important when you have these dips that you stay strong.
‘There are not many teams who have continually good days.
‘Someone said Jose Mourinho not’s doing too well at the moment.
‘You don’t have good days every day but this is a great club so we’ll dust ourselves off and go again.’
Official Brendan Malone was a central figure in Saturday’s game, booking seven players.
He also failed to send off Accrington’s Sean McConville after a first-half altercation in which he appeared to strike Ben Davies.
Cook wasn’t prepared to land any blame at the referee’s doorstep, however.
He said: ‘I get on with it. I’m not getting involved in it (commenting on the incident).
‘Did we have a penalty in the first half? We might have got that in front of the Fratton End and our fans.
‘But the referee has done nothing wrong. He makes decisions like we all do.
‘Maybe some of my decisions weren’t great, but there you go.
‘You need to be better than saying it was down to the referee.’
Cook had praise for Accrington, although he wasn’t impressed with the quality on offer in Saturday’s game.
Cook said: ‘It wasn’t good to watch. That’s how the game was. It takes two teams to have a good game.
‘If you don’t have two teams trying to play in the right spirit it will be a bitty game.
‘It was a bitty game but Accrington played well within that – so they deserve credit.’
Meanwhile, Pompey are waiting to see the severity of Brian Murphy’s injury after he went off with a groin problem at half-time on Saturday.
Cook said: ‘It’s a groin, but we don’t know how bad.’
– JORDAN CROSS