The newly promoted club are panicking as they are presently bottom of the Premier League.
Forest owner Evangelos Marinakis is looking to sack Cooper in the coming weeks, says The Sun.
Forest, who bought a whole new squad this summer, have lost five matches in a row.
The source adds that Marinakis believes the team should be at a higher level after spending £150 million on 23 new players.
Struber turned down an approach from Manchester United to join former caretaker manager Ralf Rangnick's staff last season.