Johnson turned arguably his best display yet in a red and white shirt following his £10million summer switch, combining his attacking duties with helping out at the back.
He said: "When you play for Sunderland, obviously there's a bit more onus on you to do a bit more defensive work. When you are at City, you have the ball a lot more and you can afford to play higher and not do as much defensive work.
"But I am bringing that back into my game from my Middlesbrough days. I have got to defend a lot more and I am definitely getting better and fitter at that.
"The main thing I want to do is attack and score goals, but I will never forget my defensive duties."