MANCHESTER, England -- Jose Mourinho has said Manchester City are "untouchable" on the eve of the derby but avoided questions about allegations the Premier League champions have circumvented financial fair play (FFP) rules.
The United manager said that after three consecutive wins, including an impressive victory over Juventus in midweek, Pep Guardiola knows he is in for a "difficult match."
Mourinho praised City for their work on and off the pitch after a season during which they won the title by a record 19 points, but he refused to be drawn on allegations published in Der Spiegel that their success has been built on finding ways to get around FFP rules, including organising inflated sponsorship deals.
"It is difficult for me to answer because I focus on my job, I focus on the four lines, focus on football," Mourinho told a news conference on Friday. "If you want to speak about their football potential, we can speak and football potential starts with investment.
"After that, of course, there is a quality of the work, of the organisation. I think that is untouchable but what is behind [the scenes] I cannot say.
"In this moment I have only to think about football, and to think about football is to think about Manchester City as a football team."
United were the last team to win a Premier League game at the Etihad Stadium and, despite a mixed start to the season, will head there full of confidence after fighting back against Bournemouth and Juventus to win both games 2-1.
Victory over Guardiola's side would cut the gap at the top to six points but Mourinho refused to say the derby is a chance for his team to get back into the title race.
"If we draw [the gap] is nine points if we lose it is 12," he said. "I don't think it is the way to look at the match.
"We have to just think about the match, it is difficult enough by an isolated event.
"I want to play it as an isolated match. A difficult match against a difficult team but they think it is a difficult match for them."
Mourinho also said that Romelu Lukaku is in line to feature for United against City if he can prove his fitness over the next 48 hours.
The striker has missed the last two games with a muscle problem but has returned to training and could be included in the squad for Sunday's derby.
"Lukaku is training with the team [on Friday], if this answer is positive and we have of course one more session [on Saturday]," Mourinho said.
"If the answer is positive, he's ready but in this moment I can only say he trains with the team, I don't know his answer."