Chelsea have parted company with manager Jose Mourinho by mutual consent after weeks of intense speculation over his future.
The defending Premier League champions suffered a fifth defeat in their last seven Premier League games against Leicester City on Monday, after which Mourinho said he felt "betrayed" by his players.
Although Chelsea finished top of their Champions League group with a 2-1 victory over Porto last week, the 2-1 loss at Leicester leaves them 16th in the Premier League table and just one point above the relegation zone after 16 matches.
A club statement said: "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."
Last season, Mourinho added a third Premier League title to the two he won in 2004-05 and 2005-06 during his first spell in charge of Chelsea and was rewarded with a four-year contract extension in August.
But the club's fortunes have dramatically dipped since then, with the 52-year-old cutting an increasingly strained figure over recent weeks as his side have slipped away from the top-four race and been dumped out of the League Cup by Stoke City.
Mourinho's cause has also been damaged by a handful of ugly confrontations, most notably with former club doctor Eva Carneiro, who stepped down after being publicly criticised by Mourinho for treating Eden Hazard on the pitch when Chelsea were already a man down against Swansea City.
The former Porto boss has also come into conflict with some first-team players. Striker Diego Costa threw his bib in the direction of the manager when left on the substitutes bench for the 0-0 draw with Tottenham, while he told his squad to "rethink the way they live football" after the Leicester setback.
Former Chelsea interim boss Guus Hiddink is one of the favourites to take charge on another temporary basis as the champions pursue a long-term successor to Mourinho.
Pep Guardiola, who is widely reported to be preparing to leave Bayern Munich at the end of the season, has been touted as a possible candidate, while ex-Real Madrid and Tottenham boss Juande Ramos was named as a more surprise option in some reports.
