Jose Mourinho says Sergio Aguero's absence will be a hindrance for Manchester United in the derby rather than a help.
Manchester City striker Aguero will be serving the first of a three-game ban during Saturday's derby at Old Trafford.
The ban was handed out after an FA panel found him guilty of violent conduct for elbowing West Ham United's Winston Reid.
Speaking in his news conference on Friday, United manager Mourinho said: "It changes [for us] because it is more difficult. When Aguero is available, we know that he plays, we know their formation, and their dynamics.
"Nobody has doubts. If he is ready, he will play. But now he doesn't play, they have an amazing squad in terms of options and there are many things he [City manager Pep Guardiola] could do.
"He could decide to play with [Kelechi] Iheanacho or [Raheem] Sterling. He could decide to play with [David] Silva as a fake No. 9 between the lines. It is clear that they have many options.
"That for us, in the preparation of the game, makes us have to go step-by-step with every situation because we are trying to reduce the unpredictability of the game. To try to do this now is more difficult."
Aguero had scored six goals in four matches so far this season before being handed his ban. He scored on the opening day against Sunderland, added a hat trick against Steaua and then two more goals against Stoke City.
The only match in which he failed to find the net was against West Ham.