Jose Mourinho described Manchester City's quality as "untouchable" in the build-up to Sunday's derby, with his United side nine points behind the defending Premier League champions.
City have made a stunning start to the season and are on track to defend their title under Mourinho's old foe Pep Guardiola despite Chelsea and Liverpool's similarly impressive form.
But City's preparations for Sunday's derby at the Etihad Stadium have been disrupted by a series of allegations of financial impropriety, which Mourinho addressed at his pre-match news conference.
German magazine Der Spiegel made a series of claims against City in an on-going series of articles based on documents purportedly attained from whistleblowers Football Leaks.
Der Spiegel's reporting claims Sheikh Mansour's City regime topped up multi-million-pound sponsorship deals with Abu Dhabi companies, using their owner's fortune, in order to meet UEFA's Financial Fair Play (FFP) stipulations.
Guardiola has said City want to follow UEFA's FFP rules and Mourinho suggested the club's heavy backing of the former Barcelona head coach in the transfer market has moved them into a different league to United.
"It's difficult for me to answer because I focus on my job, I focus on the four lines and I focus on football," Mourinho told reporters.
"If you want to speak about their football potential we can speak and the football potential starts with investment.
"After that there's the quality of the work and the organisation and I think that is untouchable, but what is behind I cannot say.
"In this moment I have only to think about football and about Manchester City as the football team they are."
"We are a not a team that gives up," says the boss. "We are a team that always finds a way to fight back. Sometimes changing results, sometimes not. But we are a team that has a collective spirit to fight back." #MUFC pic.twitter.com/NeB12Fj82f— Manchester United (@ManUtd) November 9, 2018
The Portuguese previously indicated United - seventh in the table going into the weekend - cannot consider themselves in the title race until they climb into the top four.
Mourinho's men cross Manchester already lagging behind their rivals, who won the Premier League title by a whopping 19 points last term, smashing a range of records in the process.
And Mourinho said United are not focusing on the yawning gap between the two clubs in the build-up to Sunday's game.
"If we draw it's nine [points] and if we lose it's 12 - it's not the way to look at the match," Mourinho said. "Just think about the match.
"It's difficult enough as an isolated event, to put it in the context of where we are then it becomes even more difficult.
"I want to play it as an isolated match against a difficult team. But I don't think they think it is an easy match for them."
Last season's derby in April saw United come from two goals down to claim a 3-2 victory, inspired by Paul Pogba's double, although Guardiola's men still secured the title later that month.
"I don't think it's special because of last season, it's special because it's the Manchester derby and it means what it means," Mourinho added.
"We are going to try. I cannot say we will be successful in our motivations and desire, but we played two difficult matches away against two very good teams, Chelsea and Juventus, and we managed to get good results.
"Even if the good results were not in our pockets the performances were there, the positive attitude was there, we are going to try. But Manchester City are a very powerful team."
|Knicks throw away 19-point lead and lose on last-second goaltending call|
|Tebow invited back to Mets´ major league spring training|
|Canelo and Jacobs agree unification fight|
|Barcelona 3 Levante 0 (4-2 agg): Dembele at the double as Barca advance|
|Levante to lodge complaint over Barcelona Copa selection|
|Kanter´s London absence ´very unfortunate´, says NBA commissioner|
|NBA could swap London for Paris in 2020|
|Spurs coach Popovich uncertain if he will return next season|
|Pistons´ Griffin fined for verbal abuse of official|
|Everton do not have financial conditions to enter transfer market - Silva|
|Andy Cole joins Sol Campbell´s coaching staff at Macclesfield|
|Atletico confirm Saul has thigh injury|
|Wood replaces injured Stone in England squad|
|Lebanon 4 North Korea 1: Disciplinary record cruelly denies Radulovic´s men|
|Saudi Arabia 0 Qatar 2: In-form Ali bags brace as Qatar top group|
|Robertson signs new Liverpool deal|
|Vunipola backs Farrell to thrive in solo leadership role|
|People don´t know what´s going on behind the scenes - Mourinho defends United stint|
|Indefatigable Muguruza knocks out Konta at 3:12am|
|Serena coasts, difficulties for Halep and Muguruza´s marathon|
|Lowry retains Abu Dhabi lead|
|Djokovic battles past Tsonga, young guns flourish|
|Louisville airport to be renamed in Muhammad Ali´s honour|
|Emery not thinking about Ozil speculation|
|Sri Lanka hopeful over Kusal Mendis finger injury|
|Oman 3 Turkmenistan 1: Last-gasp Al-Musallami guarantees progression|
|Emery wants Cech to end career ´in a good moment´|
|Japan 2 Uzbekistan 1: Shiotani stunner seals comeback and top spot|
|Calhanoglu deal ´financially impossible´ for Leipzig|
|Not seen at Aus Open since Nadal, Djokovic and Murray in 2009 – ´Next Gen´ make move|
|Martial: Solskjaer lets me express myself|
|Djokovic sees off Tsonga to reach third round|
|Returning Cousins calls Warriors ´the most hated team in sports´|
|Halep injury ´nothing dangerous´|
|Warner picks up elbow injury in Bangladesh|
|Mkhitaryan returning to Arsenal training next week|
|Leeds United pounce for Real Madrid goalkeeper Casilla|
|Watson lights up Gabba before power cut forces abandonment|
|Superb Serena blows Bouchard away|
|Tevez, Hulk, Oscar, Lavezzi - how the CSL stars Dembele is following to China fared|
|Thiem retires from Australian Open|
|Osaka ´not telling´ when it comes to injury niggle|
|Fabinho enjoying Klopp´s management style|
|Halep battles past Kenin in Melbourne|
|Hartley to miss England´s Six Nations opener|
|Dembele departs Spurs for Guangzhou R&F|
|Nacho convinced Isco remains important to Real Madrid|
|Warriors star Curry sets NBA record|
|Raonic survives four-hour marathon against Wawrinka|
|Osaka powers through to Aus Open third round|
|Irving dominates in Celtics´ win over Raptors|
|Irving called LeBron this week to apologise|
|Ajax star De Jong wants to resolve future ´quickly´|
|Payton on Rams CB Peters: I have great respect for him|
|Rockets star Harden matches Chamberlain with historic performances|
|Nishikori survives Karlovic test in Melbourne|
|Vieira reunion felt really weird - Henry|
|´#BetAgainstUs´ - Edelman and Pats embracing underdog status|
|Van der Vaart: Isco the best player in the world|
|I haven´t seen Guardiola or Klopp do that – Lampard unhappy with Bielsa|
|Real Madrid always play to win, insists Casemiro|
|Royals pitcher Skoglund suspended for 80 games after testing positive for PEDs|
|Ronaldo and Juve celebrate Supercoppa Italiana title with Mayweather|
|We are not going to talk about Morata - Simeone reluctant to discuss striker|
|Madrid weak in Leganes loss, says Solari|
|Bologna and Banvit seal Champions League play-off spots|
|LeBron James to miss Thunder & Rockets games but nearing practice return|
|Leganes 1 Real Madrid 0 (1-3 agg): Isco starts as Solari´s side go through despite defeat|
|NFL playoffs 2019: X-factor for each NFC team|
|Mahomes: Chiefs must not repeat mistakes against Patriots|