Manager Kevin Keegan has left Manchester City by mutual consent, the English Premier League club confirmed on Friday.
The 54-year-old former England and Newcastle manager had been due to leave when his contract expired at the end of next season.
"Manchester City football club announces that by mutual agreement our manager Kevin Keegan will leave the club with immediate effect. We all believe that this is in the best interest of the club," a statement on City's website said.
Keegan, who previously resigned from Newcastle and England, had only recently said he intended to stay until the end of his contract when he has always said he would leave the club.
However, uncertainty surrounding his future has been circling in recent weeks.
Keegan led Manchester City back into the Premier League in his first season in charge in 2002 after being appointed following their relegation from the top flight the previous season.
Since then City have moved to a new stadium but have failed to make any impact on the Premier League, finishing ninth and then 16th last season. They are currently 12th in the 20-team division.
"Kevin has brought stability to a club that was very much in need of solidity and consolidation," the City statement continued.
"Kevin's professionalism, infectious enthusiasm and drive for success have benefited all areas of the club.
"The board and staff of the football club would like to thank Kevin for his valued contribution to all aspects of our organisation and wish him and his family all the very best for the future."
Keegan brought the likes of former Manchester United goalkeeper Peter Schmeichel to City alongside popular creative players like Israeli Eyal Berkovic.
Manchester City winger Shaun Wright-Phillips has also flourished under Keegan to reach the fringes of the England first team.