But who can he call upon if there’s a need to keep players fit and available for the New York Stadium clash?
Well, there’s quite a lot of depth, on paper, to his squad.
And while previous Blues boss Kenny Jackett used to Papa John’s Trophy to blood his youngsters, Cowley will resist that urge as he looks to get his fringe players some much-needed game time under their belts.
Here’s how we think Pompey could line up tonight in a 3-5-2 formation.
1. Goalkeeper: Alex Bass
Gavin Bazunu's Pompey form has forced Bass to take a back seat again this season. He's only made two appearances this term while a positive Covid test result prevented him from playing the Blues' last Papa John's Trophy game at AFC Wimbledon in September. He'll be itching to show what he can do and prove to Danny Cowley that he can be his No1 next season when Bazunu returns to Manchester City.
2. Centre-back 1: Kieron Freeman
If Danny Cowley opts to go with three at the back to replicate his current preferred 3-5-2 formation in the league, then Freeman could be asked to fill one of the slots. Why? Well, firstly, Clark Robertson's injury means the Blues are short of senior cover in the position. Secondly, Freeman hasn't exactly excelled since the switch and could be handed extra game time to learn the position and the demands expected of him.
3. Centre-back 2: Paul Downing
This is the type of game Downing is always wheeled out for as he continues to be overlooked for League One selection. Yet there never appears any chance of him breaking into Danny Cowley's starting XI - much like his experience under Kenny Jackett. It cannot be good for either the player or the club. Yet two years on from his arrival and the issue remains unresolved.
4. Centre-back 3: Connor Ogilvie
The former Gillingham defender is back after a calf injury kept him out of Pompey's past five matches. Yet the form of Lee Brown means the left centre-back position seems his likely route back into the first team. Midfielder Shaun Williams has been filling in there but looks far from assured. Tonight could see Danny Cowley test Ogilivie in the role ahead of Saturday's league trip to Rotherham.