It will not be decided until tomorrow whether Rooney's troublesome ankle injury will stand up to the strain of a frenetic derby, in which United will look to retain an outside chance of retaining their Premier League crown.

City will also be trying to take a significant step towards securing Champions League football and, under those circumstances, Mancini could be forgiven for hoping Rooney does not recover.

However, in bracketing the England striker alongside his own Carlos Tevez as the best forward players on the planet - Lionel Messi excepted - Mancini hopes they are both on view.

"I want Rooney to play," Mancini said. "If people around the world are watching a game between City and United it is better for the best players to be involved.

"And, whilst Messi is the best, Messi, Tevez and Rooney are the top players in the world."

While the importance of Rooney to United has been obvious for some time now, arguably City are just as reliant on Tevez.

With 28 goals to his name, Tevez is by far the Blues' most prolific marksman, and with 10 in his last eight games the 26-year-old is hitting form at just the right time given Mancini rates the next month as the most important period in City's illustrious history.

"The last month will be fantastic for us. Maybe the most important in our history," said Mancini.

"If we finish fourth we can change the whole way our club is. To play in the Champions League next season is most important for the club and the players."

To that end, Mancini is anxious to present a united front.

Tevez has not helped that situation with his criticism of Mancini's training methods, which he feels are too tough.

However, the Italian makes no apologies for dragging his players through regular double sessions, pointing to City's present Premier League status as proof that they are working.

"This is my style," he added. "I don't think we work hard. I think we work well. Carlos has done that, like the other players.

"We have improved over the last three months. I am content about that."

Certainly Tevez's performances do not hint at the resentment that characterised his last days at United.

The Argentina star has already damaged his old club this season, scoring in both legs of the Carling Cup semi-final, even if his efforts ultimately ended in failure.

A more tangible reward lies in wait this time, which is why Mancini is hoping Tevez maintains his current form.

"Maybe Carlos wants to score in this game more than the others," said Mancini. "I just hope he plays very well, like he has done in the last few games.

"I don't want him to think about other issues. He played for United for two years and did very well for them.

"But now he plays for Manchester City and we are glad he is here with us."

Mancini's focus is solely on getting City into the top four, to the extent that he does not want to offer any opinion on the likelihood of Germany defender Jerome Boateng completing an £11million summer move from Hamburg.

Boateng is definitely on City's radar though, with Mancini accepting life in the transfer market would be easier should that lofty status be claimed.

"We must also think about the future because even if we don't finish fourth we will still be in the Europa League," he said.

"But getting into the Champions League next year would make it easier to get the players we want."

Meanwhile, Mancini has expressed surprise at the suspended £20,000 fine imposed by the Football Association for his recent touchline spat with Everton boss David Moyes.

Mancini apologised for his conduct immediately after the incident and believes his actions were nothing more serious than those of a passionate man at a time of great pressure.

"I find it a very strange decision," he said. "I apologised to David Moyes, the referee and the supporters after the game.

"I suppose I will be more careful in future."