While new signing Joe Morrell must make do with a place on the bench for the visit of Crewe to Fratton Park.
The naming of Bazunu in the Blues’ starting XI is a clear statement on who Cowley regards as his number one in goal.
Bass started the previous two matches against Fleetwood and Millwall, with Bazunu still finding his feet following a pre-season injury.
However, the former Academy product makes way for the Manchester City loanee, signifying his first appearance for Pompey.
Elsewhere, Reeco Hackett-Fairchild is rewarded for his goal-scoring outing at Millwall in the Carabao Cup with a first League One start.
Gassan Ahadme drops to the bench following successive starts, while Shaun Williams again continues after recovering from a back issue.
Recent recruit Morrell is among the substitutes, with the bench also welcoming the return of Ellis Harrison after Covid.
Yet Louis Thompson is not involved after his signing in the week.
Pompey: Bazunu, Freeman, Raggett, Robertson, Brown, Williams, Tunnicliffe, Hackett-Fairchild, Curtis, Harness, Marquis.
Subs: Bass, Ahadme, Hirst, Ogilvie, Jacobs, Harrison, Morrell.