Chelsea have axed Jose Mourinho just two days before the Premier League clash with Sunderland.
The Champions have endured a dismal defence of their title, with the Blues sitting 16th in the top flight - a point above the relegation zone.
Chelsea are just three points and three places above the Black Cats, who travel to Stamford Bridge on Saturday.
Experienced Dutch manager Guus Hiddink is the favourite to replace Mourinho on a short term deal until the end of the season.
Sam Allardyce said the demise of Chelsea was "staggering" at his pre-match press conference this afternoon.
In May, Chelsea were celebrating their fourth Premier League title - three of which had been brought to the club across Mourinho's two spells in charge.
They wrapped up the title with three games to spare as they beat Crystal Palace 1-0 at home on 2 May to finish theseason eight points clear of second-placed Manchester City.
The 52-year-old Portuguese boss is reported to have been relieved of his Stamford Bridge position just seven months after guiding Chelsea to the Premier League title.
Mourinho drove Chelsea to title and league cup success last term, only to see his team slip to nine defeats in 16 Premier League matches so far this season.
A club statement said: "Chelsea Football Club and Jose Mourinho have today parted company by mutual consent.
"All at Chelsea thank Jose for his immense contribution since he returned as manager in the summer of 2013.
"His three league titles, FA Cup, Community Shield and three League Cup wins over two spells make him the most successful manager in our 110-year history. But both Jose and the board agreed results have not been good enough this season and believe it is in the best interests of both parties to go our separate ways.
"The club wishes to make clear Jose leaves us on good terms and will always remain a much-loved, respected and significant figure at Chelsea. His legacy at Stamford Bridge and in England has long been guaranteed and he will always be warmly welcomed back to Stamford Bridge.
"The club's focus is now on ensuring our talented squad reaches its potential. There will be no further comment until a new appointment is made."