Ian Holloway has left his position as manager of Crystal Palace by mutual consent after less than a year in charge at Selhurst Park.
A 4-1 defeat by Fulham on Monday left the club five points adrift of safety.
"Ian felt that a new approach might help keep us in the division," chairman Steve Parish said.
"It's a completely different challenge for Ian and a completely different challenge for us at the club.
"Ian's been very noble and he's come forward and said: 'I can't do it.' I've spent three days trying to get Ian in the frame of mind that he can do it."
Assistant manager Keith Millen will take temporary charge for the game against Arsenal on Saturday.
Although the club lost star player Wilfried Zaha to Manchester United, Holloway was allowed to bring in 16 players during the summer.
"I have pride in the job we've both done," Holloway said.
"We need to shut up shop in this division. At the minute we've got a whole new group there.
"I have to hold my hand up and say we didn't keep the spirit that got us up.
"We changed too much too quickly."
He added: "This club needs an impetus of energy - but I just feel tired to be honest. I'm worn out."
Palace won 3-1 against fellow strugglers Sunderland on 31 August, but they have lost their seven other league games this season.
Palace are 19th in the Premier League table and speculation had surrounded Holloway's position following a meeting with Parish after the Fulham defeat, despite the chairman telling BBC Radio 5 Live before the game his job was secure.
Parish said he would consult Holloway when it came to appointing a new manager and that the club needed someone with more top-flight experience.
"We've got a whole group of people who are only really used to the Championship and dropped them into the Premier League," added Parish.
"I think we both realised we need someone with more experience at this level."
Holloway ended a three-year spell at Blackpool - who he guided to promotion to the Premier League in 2010 before being relegated back to the Championship the following season - to join the Eagles, succeeding Dougie Freedman.
Palace were fourth in the Championship table when Holloway arrived, but held onto a play-off place thanks to an 89th-minute winner from Mile Jedinak in the final game of the season against Peterborough.