The 22-year-old has scored just one league goal for the Premier League champions this season after finding a place in the starting line-up limited, and his manager is keen for all four of his strikers to step up their output if the club are to retain the title.
Balotelli's relationship with the club is fraught after taking City to a tribunal over the fine of two weeks' wages for his poor disciplinary record last term, and Mancini has now urged more commitment from the striker.
"He needs to train," Mancini is quoted as saying by The Mirror. "I don’t think he was happy about it, but when he starts to show his quality he will play again.
"We won the title last year because all the strikers scored a lot of goals. I wanted it to be the same this year. So if a player like Mario is not performing, then he will stay at home."
|CITY TAKEN TO TRIBUNAL
|28/1||Manchester City are 28/1 with William Hill to beat Reading 6-0 this weekend
However, Samir Nasri is a doubt for the visit of the newly promoted side after withdrawing during the first half of the 3-1 win over Newcastle United with a groin injury.
“We need to have all the players this month as we have a lot of games in two weeks," he added.
"I don’t think [Nasri] will be ready for Saturday. He played very well at Newcastle, I want him to play always like that because if he does, we will have fewer problems.”