Manchester City's Argentinian forward Aguero has been banned after being retrospectively sanctioned for an elbow on West Ham defender Winston Reid last month.
City will no doubt see the six-goal South American as a significant absentee, but United boss Mourino thinks the suspension is more of a hindrance than a help to his own team.
Mourinho and Guardiola have enjoyed 100 per cent starts to life at clubs they joined in the summer, but something has to give when the duo resume hostilities after going up against one another at Real Madrid and Barcelona
The Portuguese was respectful, if reluctant to talk at length, about Guardiola, calling him a "very good manager" as he focused his attention elsewhere
More of a concern to Mourinho is the absence of Aguero, which he expects will result in a tactical shift up front for the Blues.
"Yeah, it changes (my approach) because it is more difficult," Mourinho said.
"When Aguero is available, we know that Aguero plays
We know their formation, we know their dynamics and nobody has doubts - when a player like him is ready, he plays.
"In this moment, he doesn't play
They have an amazing reach (in terms of) squad options, and in our job you can have many decisions and different decisions.
"One thing is if he decides to play with (Kelechi) Iheanacho, and another thing is if he decides to play with (Raheem) Sterling
Another one is if he decides to play, for example, with (David) Silva as a fake number nine in between the lines.
"They have so many options that for us in the preparation of the game, we have to go step by step, we have to go situation after situation because we try to reduce the unpredictability of the game, you know?
"We know they have so many options that we try to do that job for the players
It's more difficult
It looks a little bit of a contradiction, but without Aguero it is more difficult."
Source : PA
Source: PA