Jose Mourinho has branded "unexpected" Manchester City before the Saturday expected from Saturday.
City won the United United last season title with a 19-point record cut with a total of 100 points, and the top of the Premier League table entering the derby, with the Reds penetrating by nine points.
Champions have faced harmful allegations this week that they sponsor artificial sponsorship agreements in an attempt to comply with UEFA Financial Play rules.
Mourinho said, about the City FFP allegations: "It's hard for me to answer because I'm focusing on my work.
"I'm focusing on the four lines, focusing on football, so if you want to talk about their football potential that we can speak, and that the potential of football starts with an investment.
"After that, of course, the quality of work, the organization, I think that is not easy to do.
"But what's behind, I can not say. But right now, I just have to think about football, and to think about football is to think of Manchester City as a football team there."
United came after winning 3-2 in Etihad last season to defer crowning the city title and Mourinho said they were going there Sunday with the intention to do the same.
He asked if United, who had won their last three games with a more aggressive approach, would go back to the city with Sunday on Sunday Mourinho: "We will try.
"I can not say we're getting our motivations, we want, but we played tough games away against two very good teams, Chelsea and Juventus, and we got good results.
"Even if there were no good results in our pockets, the performances were there, the positive attitude was there, so we're trying to try but Dinas is a very powerful team.
"If we're pulling the space, it's still nine points, if we're losing its 12, so I do not think that's the way to look at the game.
"We just have to think about the game, it's hard enough as an isolated event, if you want to put that game in the context of where we are and where we can be .
"I want to play it as an isolated game, a tough game against a tough team, but they also think it's a difficult game for them."
Romelu Lukaku has lost two last United games, but he has been trained today and will be left tomorrow before Sunday.
"Lukaku is training with the team this morning," said Mourinho.
"If the answer is positive and of course, there will be one other session tomorrow, if the answer is positive, it's ready but it's coaching with the team , I do not know his answer. "