Manchester United have confirmed that Michael Carrick has fractured his elbow.
The England midfielder sustained the injury during Tuesday's UEFA Champions League clash with Roma, when he fell awkwardly when challenging Mancini.
Scans have confirmed a break, which will rule him out until mid-December.
"Michael has sustained a fractured right elbow and will be out for up to six weeks," said a club spokesman.
The news only adds to United's midfield worries with Owen Hargreaves, Darren Fletcher and Park Ji-sung already sidelined.