Evans knows United cannot afford to play with such a carefree attitude as they did at Reading if they want to emerge from the derby with their advantage over City intact.
"We sort of had this predicament last year leading up to Christmas, where we scoring a lot of goals but also conceding a lot of goals," said Evans.
"It was something that we had to have a look at, because we are playing so open and sometimes quite high up the pitch.
"We've pushed our full backs on and that's something you have to get the right balance between.
"I'm sure that is something we will eradicate from the game, but we don't want to concede goals and give teams a chance to beat us or even take points of us.
"Whenever we do go a goal behind or two goals we never ever feel like we are out of the game.
"Being at this club you always know you're going to score goals the way the manager sets us up and the way the coaches want us to play attacking football and create chances."