Mancini has the unenviable job of trying to keep his big-name squad happy despite them not all featuring regularly.
The Italian believes City's star-studded roster do not yet have the winning mentality of their Premier League rivals - and he is working hard to change the mindset of his players as he aims to turn the club into winners.
"There are players whose only target is their day off and that is a big problem," Mancini told the Daily Mail. "You must replace them with those whose target is the win against Chelsea, then against Arsenal, then against Manchester United, who will work every day for this. Yes, there is still the day off, but you must never lose your focus even then.
"Before, at this club, there were players whose targets were wrong, but that mentality is changing. Those whose targets were wrong are the ones who have left. I tell them there is no day off now.
"The top players will play Saturday in the Premier League, Tuesday in the Champions League, Saturday in the Premier League; it is impossible to rest. Yes, there is one day you can use to recover, to have a massage, but your head must always be on the pitch and on your job.
"That is what is different about football. When I played sometimes we would have one game in a week; now there are no free moments, no time, not even for family. I understand it is important to have one day when you can forget everything, but for us right now we cannot even have that, because we are working to change the mentality of the club. If we can get this right, I will trust the players to have two days off, not one.
"I tell them hard work is not just running on the pitch, but in the head. We must think of opponents, who will we play, how we approach that game and we must make it a habit until it is normal, something that we do not have to think of doing."
Mancini admits he is playing catch-up against the likes of Carlo Ancelotti and Sir Alex Ferguson, and although he believes City are improving he still feels the team are not playing to their potential.
"For Carlo Ancelotti at Chelsea it was already there," added Mancini. "Chelsea have been at the top for so many years. They have the mentality that we need here, because when a club has been happy to play for the middle of the table, or just to survive, it is difficult.
"But I think of Alex Ferguson at Manchester United. He was probably frustrated every day for four or five years before it started improving.
"I am the same; but then when you win and you think of all you have done with your staff and your players, it must be a fantastic situation. I tell the players it is important we stay near the top of the table because anything can happen the year after the World Cup.
"At the moment, Chelsea are the best team, but they must play Champions League every week and it could be difficult come February; it depends on us to be there when that happens.
"From the time when I came here we have improved: a lot. In five months we now play more like a team but we are maybe 50 per cent or 75 per cent there, not 100 per cent yet."