Sammy Lee left Bolton yesterday after only 14 games in charge, becoming the second Premier League manager to go this season.
Bolton said the decision was taken by "mutual consent."
Bolton are in 19th place in the 20-team table with just five points from nine league games. General manager Frank McParland also left the club yesterday.
"This has been a difficult decision for all parties but we have agreed that the time is right," Bolton chairman Phil Gartside said. "Our efforts will now be to look for a replacement manager and to concentrate on the future."
Lee was appointed manager at the end of last season when Sam Allardyce suddenly quit. Lee, who had been Allardyce's assistant, took charge of the final two games of last season and 12 this season.
Under Lee, Bolton won three games, lost seven and drew four in all competitions.
Bolton did not say who would take charge for Saturday's home game against league-leader Arsenal.
Bolton are still in the group stage of the UEFA Cup and play Manchester City in the fourth round of the League Cup on Oct. 31.
Lee is the second manager to leave a Premier League club this season. Jose Mourinho parted company with Chelsea on Sept. 19, also by what the club said was "mutual consent."
Lee played 14 times for England and his club career took him to Liverpool, Queens Park Rangers, Real Osasuna, Southampton and Bolton.
Lee began his coaching career in 1993 as a reserve-team coach at Liverpool. He was appointed first-team coach in 1999 under Gerard Houllier.
Lee turned down the chance to be manager of England's under-21 side in August last year to concentrate on Bolton.