Jose Mourinho has noticed Manchester City "otouchable" before Sunday's eagerly awaited showdown showdown.
City won the title from United last season with a record breaking 19-point margin with a record high of 100 points and the top Premier League table entering the derby, with Reds trailing with nine points.
The champions have faced harmful claims this week that they artificially blown up sponsorship agreements in an attempt to follow UEFA's Financial Fair Play rules.
Mourinho, asked about FFP claims against City, said: "It's hard for me to answer because I'm focusing on my job.
"I focus on the four lines, focusing on soccer, so if you want to talk about their football potential we can talk and the football potential begins with investments.
"Then, of course, it's a quality of work, of the organization, I think it's incredible.
"But what's behind, I can not say. But at this moment I just think about football, and thinking of football is to think of Manchester City as a football team there."
United came from behind to win 3-2 on Etihad last season to delay the city's title crown and Mourinho said they go there on Sunday with the intention of doing the same.
Asked if United, who has won his last three games with a more attacked approach, will go to the toe with City on Sunday. Mourinho said, "We'll try.
"I can not say that we will succeed in our motivations, at our request, but we played two difficult games away from two very good teams, Chelsea and Juventus, and we managed to get good results.
"Although the good results were not in our pockets, the performances were there, the positive attitude was there, so we'll try, but City is a very powerful team.
"If we pull the gap, it's still nine points, if we lose it 12, I do not think that's the way to watch the match.
"We just have to think about the match, it's hard enough as an isolated event if you want to put the match in the context where we are and where we can be.
"I want to play it as an isolated match, a difficult match against a difficult team, but they will also think it's a difficult match for them."
Romelu Lukaku has missed United's last two matches, but coached today and will be judged tomorrow before Sunday.
"Lukaku is training with the team this morning," Mourinho said.
"If the answer is positive and of course we have a session tomorrow, if the answer is positive, he is ready, but he is training with the team, I do not know his answer."