Balotelli, 20, and Mancini worked together at Inter Milan in their native Italy
Manchester City's Mario Balotelli will miss three matches after the Football Association rejected the club's appeal against his sending-off at West Brom.
The Italian international was shown a straight red card for seemingly kicking Youssuf Mulumbu during City's 2-0 win.
Balotelli, 20, will be banned for the Manchester derby on Wednesday, the visit of Birmingham on Saturday and a trip to Fulham the following Sunday.
He had scored twice and picked up a yellow card before his dismissal.
An FA statement said: "At a Regulatory Commission hearing today, a claim that the standard punishment is clearly excessive from Manchester City's Mario Balotelli was dismissed.
"As a result, Balotelli will serve a three match suspension with immediate effect."
City will be disappointed to lose Balotelli just when he was starting to show why manager Roberto Mancini shelled out a reported £24m for his services.
His two goals against the Baggies were his first in the Premier League after two months out with a knee injury and City fans will have been encouraged by his understanding with Carlos Tevez and David Silva.
But, in swinging a leg at Youssuf Mulumbu minutes after getting a yellow for a tangling with Marek Cech, he lived up to the controversial reputation he developed while playing for Inter Milan.
Mancini, who managed Balotelli at the Italian club, felt the sending-off was harsh.
We will appeal against Balotelli red card - Mancini
"I absolutely do not agree with the referee about this sending-off," he said after the game. "A red card for what?"
The Italian added: "He played a fantastic game, he scored two goals, but the sending off was very strange.
"I want to know why it was a direct red card. For me this is not correct and the referee must explain.
"I am angry because I explained to [Balotelli] before the game, pay attention with the referee. I wanted to change Adam Johnson for Mario but I didn't have time to make the change."
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