The Italian international limped out of the 1-0 defeat at the hands of Parma on Sunday, and it was immediately apparent that the powerful centre-back had damaged his left knee.
After withdrawing Negro from the Italian national squad for the midweek game against USA, the Roman club put Negro in for extensive tests, which have confirmed that the cartilage in the joint had been damaged.
It is estimated that Negro will be unable to make a playing return for at least two months, and Azzurri boss Giovanni Trapattoni will almost certainly be forced to leave the player out of his World Cup plans.
