Bournemouth manager Eddie Howe has left the club by mutual consent after their relegation from the Premier League.
The 42-year-old led the Cherries in more than 450 games across two spells spanning more than a decade.
The Englishman, who leaves after talking to club officials on Saturday, said he believes it is "the right time for the club to have a change".
Bournemouth's five-year stay in the top flight ended despite a 3-1 win at Everton on the final day of the season.
"Having spent a total of 25 years with the club as both a player and a manager, this decision - made together with the club - is one of the hardest I've ever had to make," said Howe in an open letter to fans.
"However, although the affection and love I have for this football club will always remain, we collectively feel that now is the right time for the club to go in a new direction.
"Bournemouth will always be in my heart, but I firmly believe now is the right time for the club to have a change."
Bournemouth had risen from League Two to become an established Premier League team under Howe, who guided them to three promotions in six seasons.
But they lost 22 of their 38 games to finish 18th in the table, one point from safety, and return to the Championship after five seasons in the Premier League.
A number of big-money signings have not worked out for the Cherries in the manner Howe - who played more than 250 times for the club - will have hoped for.
Winger Jordon Ibe, who cost £15m from Liverpool in 2016, played only two league games in 2019-20, and striker Dominic Solanke - who arrived in a £19m deal from the Anfield club in 2019 - managed three league goals in 32 games.
The south coast club also suffered with injuries, not least experienced defender Charlie Daniels being ruled out for the season in August 2019 and promising winger David Brooks requiring two operations that saw him miss the majority of the campaign.
Cherries chief executive Neill Blake said Howe was a Bournemouth legend who has helped "transform the identity and history of the club".
He said the decision to part company was "even harder given our close personal friendship".
'What he achieved is a miracle'
Former Bournemouth boss Harry Redknapp, who managed the club from 1983 to 1992 and took them into the second tier of English football for the first time in their history in 1987, predicts Howe will be "back in the Premier League soon".
He told BBC Radio 5 Live: "I am very surprised. I felt sure he would look to get the club back up next season. The job he has done has been incredible.
"He took a club struggling in the third tier into the championship - which was a miracle - and then into the Premier, which I thought was impossible to do.
"Then for five years he had us playing incredible football, beating everybody at different times - it has been amazing.
"The stadium only holds 11,000 people, they had no right to get in the Premier League. For 100 years they were never out of division three or four. No disrespect but it would be like Rochdale, or clubs like that, coming into Premier League. It has been incredible.
"It will not be an easy job to follow him. He could not have done any more, and walks away with his head held high."
Howe's timeline as Bournemouth manager
31 December 2008 - Howe, aged just 31, takes caretaker charge with the club 91st in the Football League and facing relegation and potential liquidation. Despite starting the season on -17 points, the Cherries stay up on the final day of the season after winning the last three games.
8 May 2010 - Bournemouth are promoted to League One in Howe's first full season as permanent boss, finishing second on 83 points.
14 January 2011 - In his first season in League One, Howe takes the Cherries into the play-off positions and is courted by clubs from the Championship. He eventually leaves for Burnley. Bournemouth go on to lose on penalties to Huddersfield in the play-off semi-finals.
16 October 2012 - After 18 months without notable success at Turf Moor, Howe returns to Bournemouth. They are promoted to the Championship behind Doncaster. It is only the second time in the club's history they have played in the top two tiers.
2 May 2015 - After a 10th-placed finish in their first season in the Championship, Howe guides the Cherries to the title, pipping Watford on the final day. The season includes an 8-0 win at Birmingham and promotion to the top flight is a first for the club.
17 May 2016 - Bournemouth survive with a five-point cushion after a maiden Premier League season which saw them spend £10m on Benik Afobe and beat Chelsea and Manchester United.
21 May 2017 - Bournemouth finish in ninth place in the top flight, with Joshua King scoring 16 goals in the Premier League.
13 May 2018 - In the relegation zone at Christmas, Howe engineers an impressive recovery and Bournemouth eventually finish in 12th place.
12 May 2019 - Bournemouth are as high as sixth in early December but tail away in the second half of the season to finish 14th - 11 points clear of trouble.
1 January 2020 - A 4-0 defeat at West Ham sees Bournemouth fall into the relegation zone for the first time in 2019-20.
26 July 2020 - Bournemouth's five-year stay in the Premier League ends despite beating Everton because Aston Villa secure a draw at West Ham.
1 August 2020 - Howe leaves the club by mutual consent.