Chelsea produced a dominant display to ensure Manchester United manager Jose Mourinho's return to Stamford Bridge ended in a humbling 4-0 defeat.
Mourinho was back at the Bridge for the first time since being sacked by the club he guided to a third Premier League title in 2014-15, but he had no reason to celebrate as Antonio Conte came out well on top in their first meeting in English football.
The Portuguese's only previous match in the opposition dugout came in March 2010 when he led Inter to a 1-0 victory in the Champions League, but his second trip could not have contrasted more starkly.
Mourinho's team, without captain Wayne Rooney due to injury, were stunned when Pedro rounded David de Gea to score the quickest goal in the Premier League this season after just 30 seconds, and Gary Cahill doubled the lead after 21 minutes.
Chelsea's width and pressing penned United back inside their own half, but Mourinho may point to referee Martin Atkinson's decision not to send off David Luiz for a high challenge on Marouane Fellaini with 40 minutes played as a turning point in the match.
With their full complement, Conte's team extended their lead after the restart, Eden Hazard slotting home after 62 minutes before N'Golo Kante opened his Blues account with a cool finish, sending Chelsea into the top four, just a point off table-topping Manchester City.
United were behind before even touching the ball as Pedro latched onto Marcos Alonso's pass and rounded the needlessly onrushing De Gea to slot home in the first minute.
The hosts continued to play with greater intensity and, after Hazard drilled wide from 18 yards, their lead was doubled when the Belgian's right-wing corner ricocheted off Ander Herrera and sat up for Cahill to slam home from six yards.
Thibaut Courtois was no idle spectator, though, and had to dive to his left to keep out Herrera's 25-yard drive, quickly getting up to stop Jesse Lingard converting from the rebound.
David Luiz was lucky not to see red before half-time when he only received a booking from the referee for a reckless, high tackle on Fellaini.
Former Chelsea player Juan Mata replaced Fellaini for the second half in a change that enabled Marcus Rashford to join Zlatan Ibrahimovic up front, but Eric Bailly appeared to sustain an injury in a collision with Hazard and was forced off in the 52nd minute, Marcos Rojo taking his place.
United began to control possession but found themselves three behind when Nemanja Matic picked out Hazard on the left-hand side of the box, and the Belgian stepped inside of Chris Smalling before picking out the far corner.
With 20 minutes remaining Kante dribbled between the utterly anonymous Paul Pogba and Smalling to send a cool finish past De Gea to put the result beyond doubt.
Sections of the home support subsequently chanted Mourinho's name, but they were unable to contain their delight - encouraged by an ecstatic Conte - at a victory over their former boss and a club-record eighth consecutive unbeaten meeting with United.
