Chelsea’s frustrating season hit a new low as struggling Bournemouth claimed a 1-0 win at Stamford Bridge thanks to Glenn Murray’s late goal.
Jose Mourinho thought the reigning champions had turned a corner, but Eddie Howe’s visitors inflicted an eighth defeat of the season, the fourth at home.
Murray headed in moments after coming off the substitutes’ bench and, while there may have been a hint of offside, the Cherries deserved their win in front of Chelsea owner Roman Abramovich, who could yet wield the managerial axe.
Bournemouth won the Championship last season and Chelsea the Premier League, with the victory showing not just how far the Cherries had come, but how far the Blues have fallen.
Diego Costa started as a substitute for a second straight game, but, unlike at Tottenham, the striker was not left to brood for the entire 90 minutes and came on at half-time.
Costa’s presence was limited until he fouled Adam Smith, was denied a penalty when his cutback hit Simon Francis on the arm and then was shown a yellow card for a foul on Matt Ritchie in quick succession.
Pedro, or Costa, should have scored 15 minutes from time, but neither could get on the end of Branislav Ivanovic’s dangerous cross as Chelsea became increasingly frustrated by referee Mike Jones’ decisions.
And Mourinho will be furious when he sees the replays of Murray’s winner, which came when Thibaut Courtois flapped at a corner and the former Crystal Palace striker headed in.
Chelsea face further examinations against Porto and Leicester in the next 10 days, while the Cherries next play Manchester United.
Eden Hazard received a written report after his Tottenham display as Mourinho wanted to leave no doubt over his delight at the performance.
His first-half appraisal, continuing as Chelsea’s “false nine”, is unlikely to have been glowing.
The Belgian had a chance to end his search for a first goal of the season in his 20th game in the opening moments, but his shot was less than convincing and straight at Artur Boruc, the goalkeeper back from a six-week injury absence.
Hazard would have been marked down by Mourinho soon after, too, when he lost the ball to Smith, in for the ill Sylvain Distin, and Junior Stanislas shot. Fortunately for Hazard, Gary Cahill blocked.
Courtois was back for the first time in three months after his knee injury and soon showed why he was immediately restored, saving well from Stanislas.
Joshua King could not get the rebound away and then fired at Courtois at the near post.
The visitors attacked with pace and the Blues were vulnerable, particularly out wide.
Costa, who flung his substitutes’ bib at Mourinho at the end of last Sunday’s draw at White Hart Lane, needed help from John Obi Mikel to put on his green bib after 29 minutes before warming up on the touchline.
Chelsea were ponderous in possession and appeared to lack a presence up front, with Boruc saving from Hazard, Pedro and Oscar.
Mourinho had seen enough, sending on Costa for Oscar.
The muted half-time boos turned to applause just at the sight of the Spain striker going on.
Nemanja Matic, wearing a protective mask, should have done better than head over Willian’s cross before Jones ignored Costa’s penalty appeal before booking the striker.
Costa stretched to toe-poke Cesc Fabregas’ ball over the top, but Boruc saved.
Murray scored eight minutes from time and Bournemouth might have had two more when Ritchie and Harry Arter fired wide on the counter-attack in a memorable win.