Jose Mourinho returned to Stamford Bridge and was roundly humiliated as his shockingly poor Manchester United side were thrashed by a rampant Chelsea.
First half goals from Pedro and Gary Cahill set the Blues off and second half strikes by Eden hazard and a debut goal by N'Golo Kante completed the rout.
Thirty seconds from kick-off was all it needed for Pedro to slice open Manchester United's defence, round David De Gea and slot the ball into the empty net. It was the Spain midfielder's first goal at home since February and the visitors were royally stunned.
All the pre-match was about the 20th anniversary of the death of Matthew Harding, a Chelsea director but very much the everyman Chelsea fan, and the league return of ex-Blues boss Jose Mourinho.
But the sell-out crowd could not believe what they saw as the Blues kicked off, moved the ball around carefully before Marcos Alonso fed the ball to Pedro, who cut between United centre-back Chris Smalling and Eric Bailly, on the edge of the United penalty area, before clipping the ball past De Gea.
It was the start of a rout that Harding, watched in the stands by his family would have loved the most, the annihilation of what he would have considered one of the big boys.
Since his death Chelsea have joined that big boy club and this destruction of United was a statement that head coach Antonio Conte's developing philosophy of pressing football which defending as a team is beginning to reap dividends.
After the early setback, United responded well and should have equalised on eight minutes when a powerful right-wing run by Antonio Valencia saw the byline ball fed across the goal only for striker Zlatan Ibrahimovic head the ball over Thibaut Courtois's crossbar.
A neat corner on 14 minutes almost reaped dividends when Eden Hazard was free to smash a daisy-cutter towards goal. Unfortunately for the Belgium the ball inched just the wrong side of De Gea's left upright.
Chelsea fans went into delirium on 22 minutes when, from another corner, the ball fell off the body of Andre Herrera and into the gleeful path of skipper Gary Cahill, who pounced like a veteran striker to drill a right-footed half-volley home from close range.
Some brilliant last-ditch defending by Cahill and Courtois thwarted Herrera on the right as United went in search of a goal to get back into the game.Jose Mourinho replaced Marouane Fellaini with ex-Blue Juan Mata at half-time, with Antonio Conte kept the same starting 11.
An early shout for a penalty on 49 minutes when Bailly stuck out his leg and impeded Hazard was denied by referee Martin Atkinson. Had it been given, the defender would have been sent off and a chance to kill the game off from the spot kick given.
However Bailly injured himself in the challenge and was replaced by Marcos Rojo on 52 minutes.
A blistering 25-harder from Jesse Lingard zipped across then turf and Courtois did well to parry the zinger away on 57 minutes.
Number three and clear daylight for the home side came on 62 minutes when Hazard controlled the ball on the edge of the United area, created a one two off Nemanja matic, took one touch before arrowing the ball, low and wide of De Gea's desperate dive to his left, and the ball snuck into the inside side netting.
Even better on 70 minutes, the humiliation of Mourinho was complete when N'Golo Kante strolled through the United rearguard and slammed home a right-footer past De Gea.
Cries of Jose Mourinho rang out from all corners of the ground in appreciation of the Special One, but it was only done, once they knew the game was well and truly done.
Mourinho, responded with a quick wave.
Teams: Chelsea - Courtois, Alonso, Kante, Hazard, Pedro, Moses, Costa, matic, Cahill, Azpilicueta, Luiz
Subs, Begovic, Oscar, Willian, Batshuayi, Terry, Chalobah, Aina
Manchester United - De Gea, Billy, Pogba, Ibbrahimovic, Smalling, Lingard, Blind, Rashford, Herrera, Valencia, Fellaini
Subs: Romero, Rojo, Mata, Martial, Darrick, Young, Darmian
Referee: Martin Atkinson
Ends