Derek Llambias has walked away from his role as Newcastle's managing director as Joe Kinnear's return cast the club into fresh turmoil.
The former casino boss resigned after five years on Tyneside, amicably so on the face of it.
However, Press Association Sport understands his exit was prompted by Kinnear's appointment as director of football, a position which usurps a key part of the role he has carried out during his tenure at St James' Park.
His departure was confirmed in a brief statement on Wednesday morning, less than 24 hours after Kinnear's elevation to senior executive in charge of all football-related matters had been formally announced.
It said: "The club can announce that managing director Derek Llambias has resigned from his position with immediate effect."
Llambias, who is currently out of the country, was diplomatic in his comments.
He said: "I have had an incredible journey during my five years at the club, including some challenging times.
"I will reflect with great fondness on my time in the north-east and in me, Newcastle United have a lifelong supporter.
"I want to thank the staff for their hard work, our fans for their support of the club, and wish them all well for the future."
Ironically, it was Llambias who had welcomed Kinnear, who had referred to him as "Derek Lambeeze" in a radio interview on Monday evening, to the club on Tuesday with manager Alan Pardew keeping his own counsel.
He said: "The Board is pleased to welcome Joe back to the club.
"Joe has many years of experience working within the game, and this experience will be of great benefit to the club in achieving our objectives over the coming seasons."
Llambias' departure was predicted by Kinnear during the same radio rant when he claimed owner Mike Ashley's sidekick had resigned 10 days earlier, a suggestion which was dismissed by club insiders on Tuesday.
However, in a move which will undermine any hope of achieving the stability he and Ashley have attempted to create since teaming up at St James' Park, he has now gone, adding to the chaos which is threatening to derail Newcastle's season before it has even begun.
Llambias has provided the conduit between Ashley and manager Pardew and whether or not the former West Ham boss regards him as an ally or not, his departure will spark further upheaval at a club where the capacity for self-harm remains acute.
Ashley's right-hand man has been a divisive figure during his time at St James' and he will forever be regarded by some as a member of the infamous "Cockney Mafia" which has sparked such vitriol.
However, while he has been a central character in some of the club hierarchy's most controversial decisions - the way they treated Tyneside royalty Kevin Keegan and Alan Shearer, the decision to rename St James' and the sponsorship deal they struck with payday loans company Wonga, to name but a few - he has also played a key role in the restructuring of the business and the shrewd transfer policy which has attracted such praise.
Fans still reeling from Kinnear's appointment did not know whether to laugh or cry today.
Mark Jensen, editor of online fanzine www.themag.co.uk, said: "I can honestly say I never, ever thought I would think Derek Llambias leaving Newcastle would leave them in a weaker state than they were. But as I sit here today, that's how I feel.
"Much as Alan Pardew had a disappointing season, to bring in someone like Joe Kinnear to have more power than him on the playing side and the recruitment of players...
"You just have to really, really worry who Mike Ashley will now bring in for the departing Derek Llambias."