Morgan has sustained knee ligament damage and joins key players John Thompson, David Johnson and Michael Dawson in an overworked City Ground treatment room.
The 20-year-old has established himself as a key figure at the heart of Forest's defence this term and is a major loss for a side still very much involved in a relegation fight.
''Wes went down in training and although it looked innocuous enough at the time, he had a scan which revealed the extent of the problem,'' confirmed Hart.
Chris Doig is expected to take Morgan's place in a reshuffled Forest back-line alongside veteran skipper Des Walker.
