The 20-year-old Italian had already put City ahead from the spot after Micah Richards had been fouled before the bizarre incident. Balotelli was then sent clear of the home defence on the half hour but instead of attempting to score normally, he tried a complicated pivot, followed by a backheel which rolled wide.
Mancini immediately took Balotelli off, before sharing a few heated words with his fellow Italian. Talking to various newspapers after the match, which City won 7-6 on penalties following a 1-1 draw in normal time, Mancini said: "I hope this is a lesson for him. In football you always need to be professional, always serious and in this moment he wasn't professional."
He added: "If you are serious, you can play 90 minutes. If not, you can come and sit by me on the bench."
The striker responded with a few choice words of his own to the City chief as he made his way to the bench, indicating that he did not understand what he had done wrong.
Mancini replied, presumably pointing out how disrespectful the move had been.
Balotelli angrily took his place on the bench before throwing his water-bottle to the ground in disgust.
He did not return to the dug-out for the second half, further fuelling an already tempestuous relationship with Mancini.
"He needs to understand his behaviour has to be good in every game - not just in a final or a semi-final but every game," Mancini added.
"He knows he made a mistake. Football should always be serious and if you have a chance to score, you should score."
Source: PA
Source: PA