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.
5. Right-wing-back: Haji Mnoga
Mnoga's loan spell at Bromley hasn't exactly gone according to plan so far, so a run-out tonight against Sutton will do him the world of good and perhaps remind the Ravens what he's capable off. Mnoga will be frustrated at his lack of game time at Hayes Lane and Danny Cowley will need to ensure he's not too fired up for tonight's game.
6. Central midfield: Louis Thompson
We all knew Thompson's Pompey progress would be a slow burner because of his previous injury record, so tonight represents another key opportunity to build up his fitness. Danny Cowley has been steadily calling upon his services as his quality shines through. More game time for the former Norwich man can only be a god thing for the Blues moving forward.
7. Central midfield: Michael Jacobs
Jacobs's situation at Pompey is hard to read. Danny Cowley talks about him in glowing terms yet he remains on the fringes - much to fans' despair - after a summer move to Ipswich fell through. Maybe he's still not 100-per-cent fit after his season was cut short last term. The former Wigan man has featured just four times this season, with his last outing coming against Wimbledon last month. Tonight should be appearance number 5.
8. Left-wing-back: Reeco Hackett
Despite an impressive 11 appearances to date this season, after spending last term on loan at Southend, Hackett remains on the fringes. Danny Cowley loves his attitude, intelligence and energy, though, and feels the former Bromley man can be a worthwhile player to have around. But with Ronan Curtis and Marcus Harness currently showing good form, opportunities are limited. Cowley, though, is willing to experiment with him as a wing-back down the left. Could this be a new position for him?