Josh King's brace inspired Bournemouth to a 4-0 victory as Maurizio Sarri's lacklustre Chelsea suffered back-to-back Premier League defeats.
Cup triumphs over Tottenham and Sheffield Wednesday suggested Sarri's withering assessment of the 2-0 loss to Arsenal had the desired effect, but a section of the away supporters turned on their Italian coach at the Vitality Stadium.
Wales winger David Brooks created King's 47th-minute opener before coolly doubling Bournemouth's advantage, although he pulled up on a subsequent attack to cut a wonderful display short.
Prior to that substitution, some Chelsea fans sang "You don't know what you're doing" as Sarri withdrew Gonzalo Higuain after 65 minutes of his Premier League debut.
King's second and a stoppage-time Charlie Daniels goal means Chelsea drop below Arsenal into fifth on goal difference, while Bournemouth's first win since Christmas moves them up to 10th.
Pedro was preferred to Willian on the right wing for Chelsea and his early cross, aimed for Higuain, was headed goalwards by Mateo Kovacic, with Artur Boruc brilliantly tipping on to the crossbar.
Brooks should have done better with a 34th-minute header showed his class soon afterwards, dispossessing Eden Hazard and driving forward to force Kepa Arrizabalaga into action.
It was no surprise to see the excellent Brooks involved in the opening goal, controlling impeccably and laying the ball on a plate for King to crash home.
After N'Golo Kante wasted a chance to equalise, Brooks showed contrasting composure in the 63rd minute - collecting King's return pass and checking back inside David Luiz to crisply finish into the bottom corner.
Robbed of their standout performer, Bournemouth's liquid counter-attacks continued to flow and Junior Stanislas and King combined 16 minutes from time.
The Cherries continued to pour forward and Daniels diverted Jordon Ibe's free-kick past Kepa in stoppage time to complete an unforeseen humiliation.
What does it mean: Jury still out on Sarriball
Chelsea's head coach finds himself locked in an ideological battle with a fanbase reared on reactive, battling, never-say-die football in the mould of John Terry and Didier Drogba. Sticking to the methods that got him this job, Sarri has enjoyed success this season and has a Wembley final to look forward to next month. But 45 minutes of largely listless possession and a second-half collapse brought the naysayers to the fore.
Howe fretting over brilliant Brooks
Having confirmed top scorer Callum Wilson has undergone minor knee surgery, Bournemouth manager Eddie Howe will hope to have Brooks back on his feet before long. The elegant attacker carved Chelsea to pieces early in the second half.
Luiz's best and worst on show
Chelsea's best moments during the first half were usually prompted by David Luiz's incisive passing from deep, which injected some tempo into their play. However, the defensive pantomime that accompanied Brooks' goal will always be part of the baffling package the Brazilian brings to top-flight football.
What's next?
Chelsea entertain the Premier League's bottom side, Huddersfield Town, on Saturday, while Bournemouth also face strugglers in the form of Cardiff City.
