For Pompey’s opening game in the competition at Crawley, only Ronan Curtis started the league match against Port Vale three days earlier.
And that type of rotation is expected again as Cowley looks to get minutes into the legs of those who have been on the fringes in recent fixtures.
Several of the club’s academy youngsters could also be called upon to make up the numbers.
So who will the manager be turning to for tonight’s fixture?
Here’s how we think the Blues could line up.
5. Denver Hume
The left full-back's 45-minute run-out against Crawley in Pompey's last Papa John's Trophy game was considered an important first stepping stone in Hume's road to recovery following a back injury. Yet he's not been involved since, not even in a match-day squad. Danny Cowley has said the former Sunderland man is working very hard behind the scenes to get back into contention and will play 75 minutes at least tonight. Photo: Jason Brown
6. Reeco Hackett
The forward is keen to nail down a starting place, with eight of his 10 appearances so far this season coming from the bench. He's keen to avoid the super-sub tag so will therefore be bang up for the visit of Aston Villa's under-21s. In that respect, all eyes will be on Hackett as Pompey fans continue to make their mind up on the winger. Photo: Malcolm Bryce
7. Ryan Tunnicliffe
The midfielder has found himself back in the fold following his substitute appearance against Ipswich on Saturday - only his second appearance for the Blues in all competitions this season. Those opportunities are expected to continue with Pompey suffering midfield injury problems in recent weeks. It will now be up to Tunnicliffe to seize the unexpected chance he's been given. Photo: Jason Brown
8. Jay Mingi
The youngster is a doubt for tonight's game because of a shin injury. But with opportunities few and far between them so far this season, he will be desperate to get more game time under his belt. Another one to be considered a Pompey 'project' but from what fans have seen of the midfielder so far, they're keen for Mingi to get his Pompey career up and running properly. Photo: Simon Davies