"If you lose four out of five matches, that is not good enough," the Austrian said after Saturday's 2-0 defeat at FC Brentford. "It is time now for us to change things, for me to change things, and that is what we will do."
Glasner announced a tougher approach within the club. He said he "had the feeling that, in some areas, I may have made too many compromises". Now he would decide "what we want to do, what we have to do".
Then he put the responsibility squarely on his stars. "If the players get on board, then I think a turnaround is possible. If not, then there will be a sixth manager."
His warning pointed to the possibility that Forest could sack him if their poor results continue. The club have already changed manager five times since their promotion back to the top flight in 2022. Glasner kept his personal situation separate from the rest of the team.
"For me, that has no consequences. I think you can see that. I go home and have breakfast with my family," said the 52-year-old.
"Zero compromises!" Glasner announces tougher approach
Yet the Austrian is far from out of steam, and he does not see the Forest project as a failure.
It was "the same, excuse the word, sh*** situation as last year", Glasner said. "So you have to change things and rebuild from the bottom up. That is completely clear to me and that is what I will do. And without compromise. Zero! Zero! And if it does not work, they will let me know."
How chairman Tom Cartledge and the owner, Greek billionaire Evangelos Marinakis, respond to Glasner's words remains to be seen. The players, who have only one competitive win to their name this season, must also take them on board.
That win came on 12 September, when Forest beat Aston Villa 2-0. They lost six times either side of it: five defeats in the league and one League Cup exit. Glasner joined Forest in the summer after just two years at Crystal Palace in London. With Palace, he won the FA Cup, the English Super Cup and the UEFA Conference League. Before that, he enjoyed great success in the Bundesliga at VfL Wolfsburg and Eintracht Frankfurt.