Speculation has Nuno not being in charge for Sunday's clash with Crystal Palace after an explosive media preview on Friday.
The Portuguese has fallen out with new technical director Edu and has been critical over the make-up of the squad with just over a week of the summer market to run.
Nuno said yesterday: "I always had a very good relationship with the owner (Evangelos Marinakis). Last season was very, very, very close, almost on a daily basis. This season, not so well, but I always believe that dialogue and your opinions are always valid because my concern is the squad and the season that we have ahead of us.
"But our relationship has changed. It's not so close, it's not on a daily basis. It's not good, I think everybody at the club should be together but it's not the reality."
Meanwhile, Postecoglou is being linked with the job after his sacking by Tottenham after leading the club to victory in the Europea League.
The Australian is currently in Greece and is understood to be admired by Forest owner Evangelos Marinakis.