Neil Warnock has become the first Premier League manager to be sacked this season after being dismissed by Crystal Palace.
The 66-year-old joined the Eagles for a second time in August 2014, following the departure of Tony Pulis.
He leaves with Palace in the relegation zone after a 3-1 home defeat by Southampton on Boxing Day.
Assistant manager Keith Millen will be in charge for the trip to Queens Park Rangers on Sunday.
It is understood Palace are looking to appoint a permanent successor as soon as possible.
A club statement read: "The club would like to put on record its thanks to Neil for all his hard work and energy over the past four months."
Phil McNulty, chief football writer: "Crystal Palace's decision to appoint Neil Warnock was always laced with risk - a manager arguably out of his time in Premier League terms and favouring an abrasive style best suited to the rigours of the Championship.
"And so it has proved, making his sacking an inevitability if Palace wanted to avoid the sort of relegation threat Tony Pulis saved them from so brilliantly last season.
"How Palace chairman Steve Parish must wish he could have come to some sort of agreement to keep Pulis - and how he must wish he could lure him back now. Sadly for Palace, this seems a non-starter."
- Pulis left 48 hours before the start of the season after guiding Palace to an 11th-place finish and being named Premier League manager of the Year.
- Warnock won just three of his 16 Premier League games in his second spell in charge, giving a win percentage of 18.8% compared to Pulis's 42.3%.
- Palace are now looking for a fourth manager in 14 months since Ian Holloway's departure in October 2013.
|Longest waits for a Premier League managerial change from the start of a season|
|1992-93||15 February||Chelsea||Ian Porterfield|
|1995-96||2 January||Bolton||Roy McFarland|
|2014-15||27 December||Crystal Palace||Neil Warnock|
|2010-11||7 December||Newcastle||Chris Hughton|
Caretaker manager Keith Millen: "It is not a nice position to be in again, that's for sure. It was a surprise this morning when I arrived to get the call from the chairman to let me know the situation.
"I saw Neil this morning and we had a good chat before he went. It's a sad time and a very difficult one for all the staff because when he came in he kept us on as part of his backroom team. We are all disappointed but we have all got to move on quickly with this game coming up so soon."
Mark Bright, former Palace striker: "I had never heard Selhurst Park as quiet as it was yesterday. There seemed to be a lack of confidence. The manner of the defeat was really disappointing.
"[Palace chairman] Steve Parish will want to make a decision pretty quickly this time. He will want someone who can make an immediate impact. "
Bright was speaking on Football Focus