Sean Dyche has been sacked by Burnley after almost 10 years in charge at Turf Moor.
The shock announcement comes with Burnley mired in relegation trouble, sitting 18th in the Premier League and four points adrift of Everton with eight matches to play.
Burnley have just one win from their past seven matches, losing five times in that run, and the Clarets' board have opted to make a change for a crucial run-in.
"Firstly, we would like to place on record our sincere thanks to Sean and his staff for their achievements at the club over the last decade," Burnley chairman Alan Pace said via a club statement.
"During his time at Turf Moor, Sean has been a credit both on and off the pitch, respected by players, staff, supporters, and the wider football community.
"However, results this season have been disappointing and, while this was an incredibly difficult decision, with eight crucial games of the campaign remaining, we feel a change is needed to give the squad the best possible chance of retaining its Premier League status.
"The process of replacing Sean has begun and further announcements will be made to supporters in due course."
Dyche was appointed as Eddie Howe's successor at Turf Moor back in October 2012 and led them to promotion in the following campaign.
Though they were relegated after just one season, Dyche oversaw a successful return to the top flight and Burnley have remained in the Premier League for five straight seasons.
In that time, he has overseen two top-half finishes and led Burnley into Europe for the first time in 51 years.
Dyche was the longest-reigning manager in the Premier League but now becomes the 10th different manager to lose his job in the top tier this season.
A 2-0 defeat at rock-bottom Norwich City last weekend has ultimately proven the final straw for Dyche at Burnley, who next face West Ham on Sunday.
Games against Southampton, Wolves, Watford, Aston Villa and Tottenham are then on the horizon as the Clarets attempt to claw their way out of danger.
Burnley announced assistant manager Ian Woan, first-team coach Steve Stone and goalkeeping coach Billy Mercer have also parted company with the club.