The 19-year-old - who came on as a second-half substitute during the 2-1 success in the first leg at the San Siro - has netted 18 goals in 54 league appearances for the Italian giants.
However, the youngster has repeatedly been criticised for displaying a poor attitude, and has endured a fractious relationship with the Portuguese supremo - who returns to Stamford Bridge for the first time since leaving the Blues in September 2007.
Reports surfaced on Monday that the Italy U21 international had been omitted from the squad for Tuesday's last 16 second leg in London following another spat with Mourinho.
And, according to Goal.com, the Special One is fed up with Balotelli's behaviour.
“Balotelli wasn’t called because he had a massive argument with Mourinho. They are having a personal feud and even though Mourinho thinks he is talented, he has made it clear that he will not tolerate his terrible attitude," an Inter source told Goal.com.
“Mourinho had enough of his behaviour and couldn’t risk jeopardising the most important game of the season.”
Mourinho refused to comment on the striker during Monday's pre-match press conference at Stamford Bridge, simply stating: “Balotelli? I'll only talk about who is here.”
While the player's agent Mino Raiola denied reports that the front-man had a fight with Mourinho, but also confirmed that he was not injured.
“There has not been any fight with Mourinho and Mario does not have a physical problem that impedes him from playing," he told ANSA.
“He went to Appiano [Gentile, Inter's training ground] to train and then was told that he wasn't among those selected.
“It would be very easy for me to set fire to everything, but I believe that instead we should change tones: in the interests of the player we have to work towards the recovery of his relationship with Mourinho.
“Mario absolutely has to respect the decision of the coach, even if he doesn't agree."
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