Roberto Mancini wants Wayne Rooney to face Manchester City on Saturday – so there will be no excuses from Manchester United if they lose.
Rooney has been an influential figure for the faltering champions this season, scoring 34 goals in all competitions.
However he has been troubled by an ankle injury and sat out the goalless draw against Blackburn on Sunday.
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United would appear to need Rooney more than ever as Chelsea’s victory against Bolton on Tuesday night took them four points clear of Sir Alex Ferguson’s side with only four games remaining.
City have already beaten United at home this season in the Carling Cup with Rooney playing and Italian manager Mancini does not see why his team cannot repeat that win again.
"I think it is better if Rooney plays on Saturday," he told mcfc.co.uk "He is a fantastic player and has had an amazing season.
"He will be a danger, of course, but United have many fine players in their team – but we have beaten them once at home already and can do it again.
"I think it is best if both teams are full strength and then the side who takes the three points can truly say the best team won and there is no reason that cannot be us."
Mancini enjoys derby day and was in charge of numerous Milan battles and believes there are many similarities between the two big city clashes.
"Supporters live for these games and look forward to them more than any other match each year, " he said. "It is about passion and desire and results do not always go to form.
"Of course, this isn’t just a game about local pride, we want to finish in fourth place and every match from now until the last will be just as important.
"We need our fans to keep doing what they do each week and get right behind the team from the first minute to the last. They can inspire us to even greater heights and they have a huge role to play against United."