Cohen suffered cruciate knee ligament damage during the 1-1 home draw with Sky Bet Championship leaders Burnley last weekend and will miss the remainder of the season.
The versatile 26-year-old, who is comfortable at full-back or in midfield, joins centre-halves Kelvin Wilson (back) and Danny Collins (ankle) as a long-term absentee and Reds boss Billy Davies is working to bring in defensive cover on loan ahead of Friday night's fixture.
Greg Halford, who has been used in a variety of positions so far this season, and midfielders Andy Reid and David Vaughan will be checked ahead of kick-off after all three players missed out against Burnley.
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- Kelvin Wilson
- Danny Collins