Gennaro Gattuso has walked out on Italian second-tier club Pisa just weeks ahead of the new season due to differences with the club management.
Former Italy international Gattuso guided the Tuscan side to promotion back into Serie B last season and he threatened to quit if they did not match his ambition.
After taking charge during the first few weeks of preseason, he has now resigned "in view of, serious, constant and unacceptable problems with the club which are preventing correct and serious working conditions."
In a statement published by La Gazzetta dello Sport, Gattuso added: "The minimum conditions to be able to carry forward this work I do with passion are lacking. Difficulty is part of the job and I believe I have shown, particularly during last season, that I am not afraid of obstacles.
"But here, the mark has quite clearly been overstepped. There are new problems on a daily basis that have just piled up, right from the day the team started preseason training. Now the ambiguity at the heart of the club and with its management has clearly gone too far."
Gattuso, 38, did not go into any details about the nature of the problems, and Pisa responded with "shock and surprise" in a statement of their own on Sunday night.
"The reasons that motivated his decision, which to be honest were given to the media before they were given to the club, are surprising and certainly some things have been said in the heat of the moment," the statement, posted on Facebook, read. "We cannot understand what the 'organisational' problems might be.
"It was Gattuso who picked his staff and the programme. The club have granted him all of his wishes, to the point where we have built a squad with many players that has seen costs explode far beyond any obligations.
"With great sacrifice, the club have accommodated all of the coach's wishes. While accepting Gattuso's decision with regret, we would like to thank him from the bottom of our hearts for the effort, passion, dedication and participation he has contributed in honouring these colours."