Jack Whatmough told his team-mates to forget the Bradford setback.
The Pompey defender believes there is no time to linger on the Valley Parade collapse on Tuesday.
And he warned Charlton they are coming for their top-six spot – with their play-off ambitions very much alive in Saturday’s huge showdown.
The Blues’ six-game unbeaten run came to a close against the Bantams as they were undone by defensive lapses.
But Whatmough is adamant there is no time to linger on that disappointment with the stakes so high.
The 21-year-old is certain there will still be plenty of twists and turns in the play-off narrative, with just over two weeks of the season left.
Whatmough said: ‘There’s no time to think about what’s happened and what’s gone wrong.
‘We now have to just focus on Saturday and getting three points against Charlton.
‘Charlton are around us and teams have to play these midweek games.
‘There are some horrible games to play for them and anything can happen yet.
‘Teams can find it tough when they have to play three games in a week.
‘They’ll feel it, so hopefully teams slip up and we collect the points we need.
‘This is the time of season when teams can find it difficult. Some clubs haven’t got much to play for, either.
‘It’s down to us really, though. We have to focus on what we have to do to get the points we need.
‘The words flying around among the lads is we have to do everything we can over the last three games.’
After three games on the road, Pompey return to Fratton Park on Saturday to face fifth-placed Charlton.
Whatmough believes that’s a significant factor, with two of their final three games against play-off rivals on home soil.
A win would see them move above the Addicks, who defeated Shrewsbury on the road on Tuesday.
Their play-off rivals have games in hand on Pompey but Whatmough knows that is not likely to convert to points in the bag for all of them.
And with top-six sides still to face each other there are certain to be teams dropping points yet.
Whatmough said: ‘We’ve got three games. Three massive games. And it’s a big advantage being at home now.
‘I think people are forgetting we have had three away games on the bounce. That kind of run can be horrible.
‘But we’ve got it out of the way now and we have to make Fratton Park a tough place to come to.
‘We know what we’re capable of. Hopefully we now go out and deliver.
‘There’s everything to play for – and that’s definitely the case on Saturday.
‘They are in and around us and we want their place.
‘They will being trying not to give anything away and we will be battling for everything.
‘Hopefully it’s an exciting afternoon with us coming out on top.’