The match is the first of two between the teams within the space of four days, with the second being a crucial Premiership meeting for Usuthu in the Mother City.
They are bottom of the table and need points more than a cup run, but Johnson argues that both are equally important.
The Citizens arrive in Durban in 14th place, although they did win the MTN8 less than a month ago.
City coach Benni McCarthy could hand a debut to Tokelo Rantie, who is finally fit after his big move to the club during the off-season transfer window.
Both teams have a clean bill of health for the cup-tie in Umlazi.