Bristol Rovers boss John Ward has been replaced by assistant manager Darrell Clarke and moved to the position of director of football.
Rovers only won one of their last seven games under Ward, whose second spell at the club started in December 2012.
They are 20th in League Two and only three points above the relegation zone.
Clarke, 36, was appointed as Ward's assistant in June last year after leading Salisbury to promotion to the Conference Premier.
"It's the right time," Ward told BBC Points West. "People will look at the league position and say 'why are you doing it now?' but it's been on the cards for a long time.
"I spoke to the chairman about four weeks ago saying we need to look at it now and give Darrell the opportunity to move on - arranging pre-season games and contracts etc.
"Unfortunately we've had one or two adverse results and it looks a bit awkward but it's been in the pipeline since the start of the season."
Ward, 62, first took charge at the Memorial Stadium between 1993 and 1996, with a top-six finish in the third tier the highlight.
He returned to the Pirates 16 years later, but they only finished 16th in League Two last season and this season have never higher than 16th since September.
The team won 65 out of 155 games during his first spell, a win percentage of 42%, but it has only been 35% since his return, with 24 victories from 69 matches.
Ward confirmed he would not be sat on the bench for Saturday's game with Morecambe.
Former Mansfield and Hartlepool winger Clarke became player-manager at Salisbury in the summer of 2010 and won two promotions in three season to guide the Whites into the Conference Premier.
He was appointed as Ward's assistant nine months ago, after the departure of Shaun North, and will now take charge of a Football League side for the first time.
"I'm privileged and proud to be managing this football club," Clarke added.
"We're not in a great position with eight games to go but our destiny is in our own hands and I'm looking forward to the challenge."