The bust-up this week between Manchester City boss Roberto Mancini and Mario Balotelli has been brewing for weeks.

The Daily Star says there has been growing tension between Mancini and Balotelli over the past week. Mancini blasted the player earlier this season over his smoking and ordered him to quit.

The situation came to a head last week when Mancini discovered Balotelli has been smoking inside the Etihad Stadium on match days.

A member of Mancini's backroom staff gave Balotelli a cigarette which he smoked in the shower room following last week's home win over Chelsea.

Balotelli was hauled off at half-time before Mancini slammed his performance as not good enough.

A club source said: "This issue has been bubbling since the pre-season tour of North America, when Mario practically begged staff for fags on a daily basis."