Everton substitute Steven Naismith's hat-trick secured a 3-1 win against Chelsea on Saturday as the stuttering Premier League champions suffered their third defeat of the season.
Naismith, who came on early in the game, scored twice in the first half and capped a fine individual display with a third late on.
Nemanja Matic netted the pick of the game's goals before the break with a spectacular long-range strike, but that will be of little consolation for Chelsea manager Jose Mourinho, whose side have collected just four points from their opening five matches.
Chelsea's defence, despite being boosted by the return of John Terry from suspension, looked shaky and indecisive throughout the contest and the margin of victory could well have been greater.
Everton suffered an early blow when Muhamed Besic was substituted in the ninth minute following an awkward collision with Kurt Zouma, which allowed Naismith to enter the fray.
It turned out to be a blessing for the Toffees, though, as Scotland international Naismith made an instant impact and put Roberto Martinez's side ahead six minutes later with a well-crafted goal.
The forward deftly evaded John Mikel Obi and Matic, slipped the ball out wide to the impressive Brendan Galloway, and then got in between Zouma and Terry to guide a header past Asmir Begovic.
Everton went close to increasing their advantage twice in the space of a couple of minutes as Begovic, deputising for the injured Thibaut Courtois made two fine diving saves.
First, Arouna Kone saw his header from Seamus Coleman's cross tipped past the post, then James McCarthy's effort from distance was beaten away.
Everton's determination to capitalise on a spell of dominance was rewarded with a second goal and Naismith again was the scorer following neat build-up play involving Ross Barkley and Romelu Lukaku.
Chelsea defender Branislav Ivanovic declined to close down Naismith just outside the penalty area and the Scot responded to the space afforded him with an arrowed left-foot shot into the bottom-right corner of the net.
Equally poor closing down — this time by Barkley — allowed Chelsea to pull a goal back when Matic struck a swerving shot from 30 yards past the dive of Tim Howard and into the top corner.
Terry flashed a header over the crossbar, while Eden Hazard saw a deflected effort go just wide as Chelsea finished the half strongly.
However, Everton regained their momentum after half-time and Lukaku bustled his way into the box, but Begovic was well stationed to block his shot at the near post.
The Belgium striker, who joined Everton from Chelsea permanently in July 2014, also served as a useful outlet for the home side on the counter-attack.
Mourinho attempted to galvanise his side's attacking potency with the introduction of striker Radamel Falcao for playmaker Pedro Rodriguez.
But the final word belonged to Naismith, who has now scored a third of his 18 Premier League goals in games against Chelsea.
The 28-year-old raced on to an intelligent through ball from Barkley and produced an adept finish from a tight angle past Begovic.