Kevin Keegan on Thursday resigned as Newcastle United manager bringing to an end his second spell in charge of the crisis-hit English Premier League side.
The 57-year-old former England boss, who had only been at the helm for eight months, felt he was left with no option but to quit after falling out with the board over transfer policy.
"I've been working desperately hard to find a way forward with the directors, but sadly that has not proved possible," Keegan said in a statement. "It's my opinion that a manager must have the right to manage and that clubs should not impose upon any manager any player that he does not want.
"It remains my fervent wish to see Newcastle United do well in the future and I feel incredibly sorry for the players, staff and most importantly the supporters. I have been left with no choice other than to leave."
Keegan's future at the club had been in doubt all week and his departure was widely expected after he missed training for the third successive day on Thursday.
The northeast club had insisted Wednesday that Keegan was still their manager but revealed he was discussing the situation with owner Mike Ashley.
Some reports said Keegan - whose position was brought into question when Dennis Wise was appointed director of football in January without his knowledge - was disgruntled at Newcastle's failure to make any major signings during the transfer window, which closed Monday.
The club's only business on deadline day was the 5.7-million-pound signing of Spanish striker Xisco and the loan signing from Valencia of Ignacio Gonzalez, although Keegan had reportedly not expressed an interest in either player.
In a statement released later Thursday, the club said: "Newcastle United Football Club is sad and disappointed that Kevin Keegan has resigned.
"Over the last few days, the club has devoted itself to the discussions it has held with Kevin and as a result of those discussions, had put together a set of practical suggestions for how to move forward.
"Today, the club made it clear to Kevin that if he had any outstanding concerns on its proposals, he should raise them with the club. The club regrets that Kevin has, instead of taking up that offer, chosen to resign."
The Magpies currently lie 11th in the table after a mixed start to the new season. They held Manchester United to a 1-1 draw, beat Bolton 1-0 but lost 3-0 to Arsenal.
Keegan confirmed his decision to quit through the League Managers' Association and it came after he received a letter from club managing director Derek Llambias, which proved the final straw.
He is the second Premier League manager to quit in successive days following Alan Curbishley's resignation at West Ham on Wednesday.
Keegan's departure leaves the Magpies looking for their sixth manager in four years. There were angry protests at St James' Park at the prospect of the adopted Geordie leaving the club for a third time after his time as a player and then as manager between 1992 and 1997, and that fury will only intensify now that his departure has been confirmed.
Ashley and Wise, the man he appointed as his executive director (football) to head up the club's recruitment arm, bore the brunt of the supporters' jeers.
The club can expect more protests, especially when the Magpies return to Premier League action against Hull on 13 September.
Keegan has been idolised on Tyneside since he led Newcastle to promotion to the top flight as a player in 1982. He took over as manager for the first time in 1992, once again leading them to promotion before narrowly missing out on the title in 1995 after a rollercoaster season.
But in 1997 he quit to be followed in the hotseat by Kenny Dalglish, Ruud Gullit, Sir Bobby Robson, Graeme Souness, Glenn Roeder and Sam Allardyce.
Now Ashley will once again begin the process of finding the man to lead the club forward with David O'Leary and Everton's David Moyes amongst the favourites.