Roma will be without Leandro Castan for the next six weeks, the club confirmed on Tuesday.
The defender picked up an injury in the defeat at Sampdoria on Sunday. Subsequent tests have shown knee ligament damage.
The South American will thus be sidelined for the next month and a half.
The 26-year-old, one goal in 19 League appearances this term, joined the Stadio Olimpico outfit in the summer from Corinthians.
Roma face Juventus on Saturday in Serie A.