Midfielder Cohen is available after completing a three-match absence following his controversial red card in the defeat at Leeds this month.
On-loan defender Konchesky must serve a one-match suspension after he was sent off during the defeat to Norwich last week.
With doubts surrounding the fitness of Joel Lynch (thigh), Julian Bennett, Cohen or Chris Gunter may be asked to fill in for Konchesky at left-back.
Kris Boyd is expected to be fit, despite limping off at Carrow Road, while fellow striker Robbie Findley could come into contention for his debut after a full week`s training.
Victory over their play-off rivals on Friday would move Forest back into the top six at the expense of Leeds, who do not host Reading until later that evening.
Source: PA
Source: PA