There are fears Claudio Marchisio could be out of action for weeks or even months after he was stretchered off with a sprained knee.
The midfielder picked up a knock to his right knee during the 2-1 defeat to Sampdoria today, but carried on playing because all the substitutions had been completed.
He eventually collapsed and appeared to be weeping in agony, clutching his knee, so had to be stretchered off.
Initial reports suggest Marchisio has badly sprained his right knee and tests will be needed to ascertain potential ligament damage.
It would be a bitter blow for the Bianconeri, who have already lost Giorgio Chiellini and Nicklas Bendtner for three months.
Think you know your Italian football? Share your knowledge, tips and comments to win cash prizes in OLBG's tipster competition - £5,000 monthly.