Catania forward Martinho and Genoa midfielder Omar Milanetto have both been ruled out for a month.
Martinho was stretchered off during the 1-0 defeat to Napoli on Sunday night after apparently spraining his knee.
Tests have now confirmed the ligament in the left knee has been torn, so he will miss out on at least the Serie A encounters with Genoa, Fiorentina, Sampdoria and Udinese.
Genoa will also be without midfielder Milanetto for a month after he suffered a thigh strain during the chaotic 4-3 win over Roma.
Think you know your Italian football? Share your knowledge, tips and comments to win cash prizes in OLBG's tipster competition - £11,000 to be won monthly!