Kenny Jackett will give some of his players a chance to impress on Tuesday night.
He will be making changes to his side for the second Checkatrade Trophy group stage match against Crawley.
Pompey go into the Fratton Park contest with one point on the board, while their opponents have yet to get off the mark.
And Jackett hopes that they can restore some confidence following Saturday’s league defeat to Oldham.
The Blues boss said: “We played them in pre-season, so both sides will be aware of the threats that the other possess.
“I’m sure, like us, they’ll make some changes, but we want to go into Sunday’s game with some positivity and momentum.
"We’re at home and we want to do well and try to progress, while also trying out some combinations."
“There are a few of the lads who have been on the bench and not had too much of an opportunity so far this season.
“We’ll obviously follow the rules and regulations of the competition, but some – especially in the forward positions – will have a chance to stake their claim.
“We’re at home and we want to do well and try to progress, while also trying out some combinations ahead of our next league fixture.”
Pompey currently have several injury concerns ahead of their next League One match at Gillingham on Sunday.
Nathan Thompson was the latest addition to the treatment room after suffering a nasty head injury at the weekend.
Jackett said: “He had concussion, so you assess him after seven days and we’ll have to see whether he’s okay for Sunday’s game.
“Brett Pitman will miss Tuesday because he’s had surgery on his broken nose, but will hopefully be back to face Gillingham.
“The only other one we’ll be looking at to see whether they can make it is Christian Burgess because Damien McCrory has an operation on Wednesday because of some cartilage problem.
“We have to come through these problems and it’s about the players who are available, even if some have to adapt to different positions for the team.”