Manchester United have slipped to an embarrassing 4-0 defeat to Chelsea on former manager Jose Mourinho's return to Stamford Bridge.

The Blues scored twice in either half as they cruised to a comfortable victory against their old boss - just the second time the Portuguese has witnessed his side ship four or more goals in a Premier League game.

Mourinho, who won seven titles - including three Premier League crowns - during his seven years in West London, could do little to alter the end result as United's poor run at this ground continued.

It is still just the one win for United here in the past 14 years, and their afternoon got off to the worst of starts when Pedro latched on to a Marcos Alonso pass around the back and simply rounded a stranded David de Gea to open the scoring.

The Red Devils, so solid defensively six days ago at Anfield, were looking disjointed at the back throughout the opening 45 minutes as the hosts put together attack after attack.

That Pedro strike summed up United's problems at the back, with Daley Blind losing his man and Chris Smalling also switching off just 30 seconds in - the quickest goal of the season so far and just the sixth the visitors have conceded inside the opening minute in their Premier League history.

Chelsea nearly had a second when, from a well-worked set-piece routine, Eden Hazard was picked out completely unmarked just inside the box and slipped the ball a yard or so wide.

There was a second 21 minutes in, however, when Gary Cahill blasted the ball over the line after it fell nicely into his path from a deflected corner into the box.

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The Blues' fluid front three in this now-favoured 3-4-3 formation were causing all sorts of problems as the half wore on - Pedro shaking Blind off the ball and seeing his cutback well blocked by De Gea, before Costa was denied on the spin by his Spain international teammate.

United did have chances of their own, though, with Zlatan Ibrahimovic outjumping Cesar Azpilicueta only to loop his header over the bar, while Ander Herrera and Jesse Lingard - in for Ashley Young in the only change by either side today - were denied by Thibaut Courtois in quick succession.

As good as Chelsea looked in attack the visitors were often the victims of their own undoing, as Marouane Fellaini was shoved high up the pitch which left Herrera often stranded on his own in front of the back four.

Mourinho inevitably turned to his bench for the second half, replacing the ineffective Fellaini with Juan Mata - another player with strong Chelsea links - and pairing Marcus Rashford with Ibrahimovic in a switch to a more traditional 4-4-2.

United were being allowed to dominate possession in the early stages of the second half with the Blues knowing that chances would arise on the counter, but that tactic almost backfired an hour in when Lingard tested Courtois with a venomous shot from range.

Openings were proving to be far harder to come by for most of the second period, but it was Chelsea who scored the killer third goal moments after that Courtois save thanks to a slick passing move.

A quick one-two saw Matic slide in Hazard, who tucked the ball past De Gea with ease to make certain of the points - the Serbian's fourth assist in nine outings already this season, compared to two in 33 last term.

There was even better to come for the Blues, too - N'Golo Kante once again highlighting the fragile nature of the opposition's midfield by simply waltzing through and delicately placing the ball past De Gea to make it four.

Chelsea, who were perhaps fortunate to see David Luiz avoid a red card for a studs-up challenge on Fellaini in the first half - the only blemish on their result - came close to conceding in the final 10 minutes when Courtois was needed to deny Ibrahimovic on the spin.

That save from Courtois, plus one at the death from Marcos Rojo's drive, ensured that Chelsea made it three clean sheets in a row in the Premier League for the first time in 18 months, and nine goals now scored at the other end since switching formation.