Usuthu will host the MTN8 champions at 19h30 in the Telkom Knockout last-16 at King Zwelithini Stadium in Umlazi tonight.
The two teams, who are both struggling in the Absa Premiership after eight games apiece, will revive hostilities in the league at Cape Town Stadium on Saturday.
"Fortunately or unfortunately, the only fortunate thing for AmaZulu is that we got the home draw which makes it more difficult because at home we have been doing very well," said Johnson, whose bottom-placed club were recently docked six points on FIFA's orders due to a payment dispute with their former player Phinheas Nambandi.
"We play some good football at home. The unfortunate thing is that it is a double-edged sword for us because we are playing them in the cup and we are playing them in the league on Saturday.
"Both of the games are important for us; the one being that we would also like to go as far as we want to in the Telkom, but the other being that we also would like to get points on the table as AmaZulu.
"The problem is that, the one is the cup and the other one is another cup. But the one is a longer cup and this one is the shorter cup. Four games and you are in the final. The other one is 10 games and you don't know where you are going to be.
"So we need to fight with that as we always do now as AmaZulu. We take it one game at a time and we treat each game as a final. We are going to treat today's game no different."
Johnson says the Citizens, who won the TKO in their first year of existence in 2016, are playing good football under coach Benni McCarthy.
"I don't know if I can call it an 'up', but they are definitely playing a good brand of football," he said.
"Benni has won his first trophy [as a coach] and we respect him for that. We know what it's like to not win a trophy or not to have the position you would like to be in.
"So we have all those expectations for us and we also have a lot of areas to improve on. We also have lot of things to show the people of Durban. We are building slowly, slowly.
"The best thing you can do is try and get as far as we can in the competition. When you get that far then the people start realising, 'Ohh, we are getting somewhere.'
"Cape Town, we know they're on the up, but in Durban we also want to prove that we are on the up. So it's going to be a nice fight as far as football is concerned."
AmaZulu last won the tournament in 1992 when it was known as the Coca-Cola Cup. Clive Barker's charges won the final 3-1 against Kaizer Chiefs courtesy of goals from George Dearnaley, Simon Magagula and Ephraim Mwale.
Since Telkom started sponsoring the event in 2006, the furthest Usuthu went was the semi-finals in 2009 where they lost to beaten finalists Ajax Cape Town.