Fenerbahce coach Jose Mourinho is reportedly a candidate to take over at Forest. He has been critical of Marinakis and technical director Edu in his recent press conferences.
Nuno has been unhappy with the state of his squad and the limitations on his ability to buy and sell players.
Mourinho and former Tottenham manager Ange Postecoglou are mentioned as potential successors to Nuno. While Mourinho is currently under contract at Fenerbahce, Postecoglou is a free agent.