It's hard to pinpoint exactly what went wrong for Jose Mourinho on his nightmare return to Stamford Bridge, so numerous were Manchester United's problems.
The Portuguese oversaw a catalogue of defensive errors as old club Chelsea thumped his current side 4-0, his defence torn apart by Pedro, Gary Cahill, Eden Hazard, and N'Golo Kante.
Question marks could be raised over United's team selection and overall shape, and whatever excuses Mourinho has to offer, his players simply didn't perform on the day.
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Having played so well on Thursday night in the Europa League, it was thought Michael Carrick might have worked his way into contention for a start against the Blues. Instead, a midfield pairing of Marouane Fellaini and Paul Pogba had little impact on the game.
Many United fans may well point to Carrick's absence as a big factor in such a heavy defeat, as the former England international could have offered more solidity in the centre of the pitch.
However, ex-Arsenal and Germany attacker Lukas Podolski had a rather different, unusual interpretation of events, albeit one that was a little tongue-in-cheek.
The 31-year-old clearly thought this was a great time to pledge his support for his international team-mate, Bastian Schweinsteiger, who is still in exile at Old Trafford.
Take a look:
There are plenty of things Mourinho could have done differently that might have affected the result, but it's safe to say playing Schweinsteiger probably wasn't one of them.
United have problems
All the same, the Special One had better get used to this kind of treatment having failed so spectacularly against his old employers. When even Lukas Podolski's rinsing you on social media, you've had a pretty bad afternoon.
It'd be great to know what Schweini's thinking right now, but seeing as nobody ever sees or hears from him anymore, we'll almost certainly never know.
It's no surprise that Podolski saw United as an easy target, though, as they've got some serious problems. The Red Devils are now five points off the top four after nine games, and up next, there's the small matter of welcoming Manchester City to the Theatre of Dreams for the EFL Cup on Wednesday.
Will Manchester United finish in the top four? Have your say in the comments.