John Collins has rocked Hibernian by walking out on his job after just 14 months as manager of the Scottish Premier League club.
Collins announced his departure at a Thursday news conference
Collins told the players of his decision at training on Thursday and cited spending limits on new players as the reason behind his departure.
"I have taken the club under the current resources available as far as I can," said the 39-year-old.
A Scottish FA spokesman insisted it was unrelated to the vacant national job.
Collins, capped 58 times for his country, has publicly distanced himself from that job, stressing that it was too early in his career to go into international management.
But the move will now spark speculation that the former Celtic, Everton, Fulham, Hibs and Monaco midfielder is set to take over as Scotland boss following the exit of Alex McLeish to Birmingham.
He has put his heart and soul into the club and we all tried to persuade him to stay
Collins announced his departure only 24 hours after helping officially open the club's new £4.9m training complex in East Mains, alongside chairman Rod Petrie and owner Sir Tom Farmer.
Asked then about the national job, he stressed that his contract, which was due to run until the end of next season, meant any talk of him becoming Scotland manager was speculative.
But, on Thursday, Collins explained that he left Easter Road with his side sitting fifth in the SPL because of the lack of a transfer budget.
"The team needed investment, there had been a lot of money brought into the club in the last 13 months, huge amounts of money which the club couldn't refuse," he said as he quit his first job in management.
"The board of directors have done a great job for the club, they've got difficult decisions, but I felt maybe now was the time to up the budget a little bit.
"My mind was made up. It was a very difficult decision. I was getting frustrated and it was time to move on.
"During my time as manager, we have brought in over £8.8m and paid out £360,000 in compensation on new players.
"I feel that I leave with the CIS Cup in the trophy cabinet, a fine set of young players, a great new training ground."
Collins led Hibs to their first major trophy in 15 years - only five-and-a-half months after taking charge at the club where he started his playing career.
He had been brought in following Tony Mowbray's departure for West Bromwich Albion and that comfortable 5-1 victory over Kilmarnock earned praise for the way he had continued to develop Hibs' young squad.
Collins' tenure will also be remembered for the public apology to him by the first-team squad following dressing-room dissent ahead of the Scottish Cup semi-final.
A delegation of players had met Petrie to complain about training methods and team selection ahead of the game Hibs lost to Dunfermline Athletic.
Hibs went on to finish sixth in the SPL, but Collins was frustrated by the lack of funds made available following the sale of Kevin Thomson and Steven Whittaker to Rangers for £4m and their Scotland colleague, Scott Brown, to Celtic for £4.4m.
Club chairman Rod Petrie insisted to BBC Sport that his board had been willing to back Collins in the transfer market.
"It came as a shock to the board," he said.
"He has put his heart and soul into the club and we all tried to persuade him to stay, but we now have to find a manager who does want to be manager of Hibernian Football Club."