Cambridge United have sacked head coach Mark Bonner following Tuesday's 3-0 home defeat by Lincoln City.
The U's only escaped relegation on the final day of last season and are currently 18th in League One.
Cambridge-born Bonner, 38, was appointed in January 2020, initially as interim boss, and agreed a new "long-term" contract in September.
The U's are the seventh third-tier team to change managers this season - and 21st in the English Football League.
Owner Paul Barry said Bonner would go down as "one of the most important people in the history of Cambridge United".
"All of us - owners, board, staff, players and fans - know how lucky we have been to have him and how hard this decision has been," Barry added.
"Cambridge United has made huge strides on and off the pitch over the last five years and Mark has been instrumental in building our strong foundations for the future, creating special memories and moments for all of us along the way - most notably promotion during lockdown, Newcastle away in the FA Cup and the great escape last season.
"He has done it through his leadership and energy, his talent as a coach, his natural communication and empathy, and his desire to push the club forward on and off the pitch as someone born and brought up in Cambridge, who genuinely cares about our city and its communities.
"But in football, sometimes you do have to make decisions you believe are right for the long-term future of the club - difficult though they can sometimes be."
Barry Corr and former Crawley boss Kevin Betsy have been put in charge of the first team on an interim basis.
The defeat by Lincoln was Cambridge's third in a row - a run which began with a 5-0 thrashing at Peterborough in the Cambridgeshire derby.
They have only won one of their past 13 league matches.
"We're really disappointed because it's been a bad few days for us," Bonner told BBC Radio Cambridgeshire after the defeat by the Imps.Listen to Mark Bonner's post-match interview following Lincoln defeat
"It's nothing that can't be fixed if everybody rolls their sleeves up, has a little bit of belief in themselves that they can do it.
"We're definitely a few wins short of where we should be but on the one hand we have to remember who we are, because playing at this level is tough for us, and on the other, do better than we have if we want to make sure we are a team that's having a more comfortable season."
Bonner first joined the staff at Cambridge almost 20 years ago and was assistant head coach under Joe Dunne and Colin Calderwood before taking charge when the latter left the club.
He was confirmed in the head coach role in March 2020 and led the team to promotion the following year by finishing second in League Two.
They also achieved one of the best results in the club's history when they won 1-0 against Newcastle at St James' Park in the third round of the FA Cup in January 2022.