Lazio full-back Stephan Lichtsteiner has fractured the third metacarpal bone in his right hand.
The defender fell awkwardly during Tuesday's training session and was taken to hospital for x-rays when the swelling did not go down.
A statement from the Biancocelesti website confirmed a fracture of the third metacarpal bone in his right hand.
It is possible he'll be able to play on Saturday against Genoa with the aid of a protective cast, but more tests will be needed over the next few days to decide if he can make it.
Think you know your Italian football? Share your knowledge, tips and comments to win cash prizes in OLBG's tipster competition  - £5,000 monthly.