Bottom of the table Sunderland beat Chelsea 2-1 and ended Blues manager Jose Mourinho's 77-game undefeated home run in one of the Premier League's biggest ever shock results.
Mourinho's unbeaten league record at Stamford Bridge, unparalleled in English football, stretched back almost 10 years to the Portuguese's arrival in west London in 2004.
Chelsea missed the chance to go top of the table with the defeat, while Fabio Borini's 82nd-minute winner from the penalty spot kept alive Sunderland's faint hopes of avoiding relegation.
Chelsea are through to the Champions League semi-finals on away goals after drawing 3-3 on aggregate with Paris St Germain. The Blues won Tuesday night's second leg at Stamford Bridge 2-0.
Jose Mourinho has branded Arsene Wenger a "specialist in failure" as he hit back at the Arsenal manager for suggesting the title was "Chelsea's to lose".
"He is a specialist in failure. I'm not. So if supposing he's right and I'm afraid of failure, it's because I don't fail many times. So maybe he's right. I'm not used to failing," the Chelsea manager said.
"But the reality is he's a specialist because, eight years without a piece of silverware, that's failure. If I did that in Chelsea I'd leave London and not come back."
Chelsea currently top the Premier League table sitting just one point above Arsenal.
Chelsea manager Jose Mourinho will come face-to-face with his former understudy Tottenham manager Andre Villas-Boas when the two teams meet at White Hart Lane today.
Villas-Boas, 35, worked under the Blues boss for seven years at Porto, Inter-Milan and Chelsea but his relationship with his former mentor has since broken down.
Speaking ahead of the clash, the Spurs boss said: "I don't lose any sleep. We had a great personal and professional relationship before. We don't have that now."
Meanwhile, Mourinho stayed uncharacteristically silent when asked about his relationship at a pre-match press conference on Friday, "I've got nothing to say", he told journalists.
The match between Tottenham and Chelsea will kick-off at 12.45pm.
Jose Mourinho said he wants to be loved for what he does in his second stint as Chelsea manager, rather than the first, but is under no illusions about the size of the challenge facing him:
Jose Mourinho described himself as "the happy one" as he addressed the media for the first the since being appointed Chelsea manager for the second time.
Jose Mourinho will speak to the media for the first time since his appointment as Chelsea manager at Stamford Bridge at 1.30pm.
At the start of Mourinho's previous stint as Blues boss in 2004, the Portuguese famously declared himself the "Special One".
Jose Mourinho will be formally unveiled as the new Chelsea manager today, just under six years since he left the club by mutual consent.