Balotelli allegedly went on a night out in Liverpool which lasted until the early hours of Friday morning despite having a game against Bolton on Saturday afternoon. That would be a breach of Mancini's rules and the City boss has said he will investigate.
Mancini, speaking after Balotelli started and scored in City's 2-0 win at the Etihad Stadium, said: "This is Mario, I don't know whether this is true. I only heard about this at the stadium because I never read the newspaper. Tomorrow I will speak with him - I am really disappointed about this."
He added: "It is not correct, not only for me and the squad but for him, because he is a professional player.
"He can't stay outside the house two days before a game until two o'clock. If it is true we will do the maximum fine that we can."
If true, the matter would merely be the latest in a long line of on and off-field controversies concerning Balotelli.
The 21-year-old has already found himself in trouble for breaking a curfew once this season having been spotted in a Manchester restaurant late at night less than 48 hours before the December loss at Chelsea.
Most infamously this season fire crews were called to his house after fireworks set off from his bathroom sparked a blaze.
He looked determined not to let the latest headlines distract him as he caused Bolton considerable problems. Yet he spurned a glut of chances before eventually finding the net in the 69th minute to secure a victory that put City five points clear at the top of the Barclays Premier League.
Mancini said: "Mario played well, he had a lot of chances. Maybe next time if he goes to sleep early he can score three or four goals."
Source: PA
Source: PA