Neil Warnock quit as manager of ailing English giants Leeds United on Monday just over a year after he took up the post.
Warnock, 64, who replaced the highly-regarded Simon Grayson when he was sacked in February 2012, leaves with the club just five points above the relegation zone in the second tier Championship.
Having been hired to restore the club to the Premier League, from which they were relegated in 2004, Warnock is walking away early from a contract which expires at the end of the season.
"We need to look to the future and the search for his (Warnock's) replacement is underway," said Leeds chief executive Shaun Harvey.
"There is no fixed timescale as securing the services of the right person is the primary objective to give us the best chance of promotion next season.
"We would like to thank Neil for his efforts during his time as our manager and share his disappointment that we could not achieve promotion."
Warnock, who has made a habit of guiding clubs to the Premier League, had already said that he would leave if it became impossible for Leeds to get promotion this year and that he woulud not be aroudn next season.
And three successive defeats, culminating in Monday's woeful 2-1 home loss to Derby County, left him little choice but to leave.
His post-match remarks had a valedictory ring about them.
"We are not going to get into the play-offs now so it is a good time to put somebody else in charge until the end of the season," said Warnock, who also had cited in the past the difficulty of juggling his job with his family being based in Cornwall in the south west of England.
"I don't think they should rush into a permanent appointment because there are no outstanding candidates at the moment, but there will be in the summer.
"I have been a manager for 33 years and this last 12 months have been the hardest. I have given it my best shot but being honest we haven't been good enough in the final third of the pitch.
"I have not resigned at this moment but I am speaking to the owners and I think a statement will be made in due course. It would appease the fans if I go now and I will recommend putting Neil Redfearn (Development Squad Manager) and Gwyn Williams (technical director) in temporary charge until the end of the season."
He has already held talks with Leeds owners GFH Capital, a Dubai-based equity group which bought the club from Ken Bates in December, about possible successors.
Warnock leaves Leeds 12th in the table and facing a relegation six-pointer against Charlton, who have two points fewer, on Saturday.