Jose Mourinho's return to Stamford Bridge proved to be a disastrous one as Manchester United succumbed to a 4-0 defeat at the hands of Chelsea.
The Blues ran riot against the Red Devils, taking the lead inside 30 seconds thanks to a strike from Spain winger Pedro.
Defender Gary Cahill doubled Chelsea's lead before the break, while goals from Eden Hazard and N'Golo Kante put Antonio Conte's side in dreamland.
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It was a truly horrendous performance from United, who now have just three days to put things right before playing host to Manchester City in the EFL Cup.
But what really went wrong for Mourinho and co. in west London? Well, unsurprisingly, United fans were extremely vocal on social media and have made their feelings quite clear.
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Here are six things United fans are angry about:
Marouane Fellaini starting
Belgium international Marouane Fellaini just hasn't been able to prove his credentials in Manchester and it's fair to say that fans were less than impressed with his performance against Chelsea.
In fact, Fellaini struggled so much that Mourinho opted to replace him with Spaniard Juan Mata at the interval.
The ex-Everton man enjoyed a steady outing against Liverpool at Anfield on Monday night but looked out of place against the likes of Kante and co.
Defence all over the place
Despite the Red Devils' lack of attacking threat on Monday, they were praised for their rock solid backline.
United limited Jurgen Klopp's side to just a couple of opportunities, but the likes of Daley Blind and Chris Smalling were abysmal this afternoon.
Even the usually so reliant David de Gea endured a torrid afternoon, making a mistake for the opening goal of the game.
Swede Zlatan Ibrahimovic enjoyed a wonderful opening to his Old Trafford career, but things have taken a turn for the worst in recent weeks.
For one reason or another, he just hasn't been able to stamp his mark on the pitch and much of that is arguably down to being left isolated in attack.
Despite the likes of Paul Pogba, Jesse Lingard and Marcus Rashford on the pitch, Zlatan wasn't given much help.
David Luiz challenge
After such a poor performance, there's not much that Mourinho can complain about but he may feel aggrieved that Brazilian David Luiz was allowed to stay on the pitch.
With his studs showing, Luiz put in an extremely poor tackle on Fellaini and probably should have been shown his marching orders.
Despite scoring in mid-week against Turkish outfit Fenerbache, Pogba's United career just hasn't taken off.
The France international may well have arrived at the Theatre of Dreams as the world's most expensive player, but he just hasn't been able to express himself on the pitch.
Michael Carrick on the bench
There's one argument that Pogba would improve if he was alongside Michael Carrick in midfield.
At 35, Carrick may well be approaching the latter stages of his career, but he's arguably still one of the outstanding midfielders in the country. Ultimately, though, he once again had to settled for a place on the bench against the Blues.
United fans: what else frustrated you during the game with Chelsea? Have your say below!