Joshua King inspired Bournemouth to one of their biggest wins in their history, with the Cherries thumping a helpless Chelsea.
Two goals and an assist from King, with David Brooks and Charlie Daniels adding a late goal for the hosts.
Gonzalo Higuain made his Premier League debut for Chelsea, but was largely ineffective at the Vitality Stadium.
Image via Premier League
Chelsea had a brilliant first-half, without scoring, really. They dominated the Cherries - but every time they got through on goal - Artur Boruc was in fine form.
Mateo Kovacic almost gave Chelsea the lead with a close-range header but it was an excellent save from the Pole in the sixth minute.
For all of Chelsea's possession, they didn't create many chances other than that in the first-half.
Right after the restart, Brooks found King, who slammed home past Kepa Arrizabalaga.
Higuain's debut was cut short on the hour-mark. The Argentine striker failed to register a shot on goal, but he linked up with Eden Hazard well.
King, who was looking very lively after the break, found Brooks, who got away from David Luiz with ease before doubling Bournemouth's advantage.
The Vitality was rocking. It was the most clinical and exciting play they've perhaps ever seen their Bournemouth side display in the Premier League.
King collected a square pass from Junior Stanislas and then notched his second and the Cherries' third.
In stoppage-time, Daniels met a Jordon Ibe delivered free-kick to inflict even more pain on a woeful Chelsea.
The Managers
Bournemouth boss Eddie Howe: "We hoped to give the best account of ourselves as possible, and one aspect of our play was very good. Our counter-attacking was superb tonight in both the first-half and second-half - the first-half without any reward, the second-half we got the goals.
"It was a brilliant defensive display. So many players throughout the team really excelled in that discipline, so it's been a good night."
Chelsea head coach Maurizio Sarri: "I am not able to explain (the game) because we played very well in the first-half. We conceded the goal very early in the second-half but we had 43 minutes so all we needed to do was continue to play.
"Maybe it's my fault because maybe I'm not able to motivate this group and these players. I don't know why. But I need to understand and we need to understand very soon because we have to play in three days."