Cohen missed the 1-0 win at Millwall on Saturday with a thigh strain and the versatile 26-year-old faces a race against time to be fit for the potential promotion showdown with East Midlands rivals Leicester at the City Ground at the weekend.
Reds boss Billy Davies told the club's official website: "Chris has a slight thigh strain and is touch-and-go for Saturday.
"I thought about putting him in (against Millwall) but if it ripped, he would be out for six or seven weeks.
"So we decided to rest him. There is a chance he might be back at the weekend."
Forest go into the game outside the play-off places on goal difference, level on points with Bolton and one point behind fifth-placed Crystal Palace.
Leicester must do something they have not done since 1972 and win a league match at the City Ground if they are to have any chance of finishing in the top six, and even a victory over Forest would leave them relying on results elsewhere to go in their favour.
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