The Ghana international suffered ligament damage while playing football on the beach with some friends and will be out of action for at least five months
The 27-year-old Ghanaian joined the Rossoneri on loan from Inter during the January transfer window and impressed during the second half of the season. Indeed, Milan were ready to offer Muntari a two-year contract worth €3 million per season.
However, the player suffered anterior cruciate ligament damage while enjoying a kick-about with friends on the beach and was forced to undergo surgery on Tuesday, thus ruling him out of action for five months.
Milan, who were plagued by injuries last season, were therefore forced to sign Kevin Constant on loan from Genoa as a replacement and, according to Corriere dello Sport, Galliani is enraged by the unexpected but essential extra expenditure.
Consequently, the paper claims that the contract offer on the table for Muntari will be €1.3 million less than the previously agreed figure.
The former Portsmouth man, whose contract with Inter will expire at the end of the month, made 13 appearances for the Rossoneri last season, scoring three goals.