Darren Ferguson has left Peterbrough United.
The Posh were one of the favourites for promotion this season but have slipped away and a 3-0 loss at MK Dons on Saturday left them fifteenth in the table.
Peterborough owner Darragh MacAnthony said to his club's website: "It saddens me to say that the club has this evening parted ways with one of the finest managers in our clubs history. After Speaking with Darren, he feels that a new challenge is needed for both himself and the football club.
We have had over 8 incredible years together with tremendous success on and off the field. I will be forever in his debt for the great times, fantastic football and professionalism he has brought to our football club. I also have no doubt that wherever he goes next, it will lead to great success for him and the club he next works for."