Manchester United's encounter with Chelsea served up a terrific match that saw three goals, three first-half substitutions, two red cards, and seven yellow cards - it was a cracker.
The game took just five minutes to explode into life when Blues goalkeeper Robert Sanchez was sent off after his rash swipe at Bryan Mbeumo on the edge of the box was deemed a goal-scoring opportunity by referee Peter Bankes.
The referee had an extremely busy day, and the red card set the tone for the match.
Enzo Maresca quickly took drastic action after the dismissal, with Estevao, Pedro Neto and Cole Palmer all leaving the field as a result.
The chaos then continued, with Bruno Fernandes and Casemiro profiting from Chelsea's defensive errors, undoubtedly due to the wholesale changes made just minutes into the game.
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United's Brazilian midfielder would then follow Sanchez down the tunnel after he earned his second yellow card as he pulled back fellow countryman Andrey Santos.
Trevoh Chalobah rose high from a corner to make Old Trafford nervous, but it was ultimately too much to ask for Maresca's side, who were at sixes and sevens for much of the encounter, and the game finished 2-1.
With that being said, here are three things we learnt from the clash.
Robert Sanchez must be replaced
Robert Sanchez was sent off just five minutes into the game
|REUTERS
Sanchez has had a catalogue of mistakes during his short career at Chelsea, but his red card at Old Trafford could be his most significant.
His dismissal was costly and caused a catastrophic run of events for the Blues that saw three first-half substitutions and two goals for United.
Maresca's side had been said to have lodged a bid for AC Milan goalkeeper Mike Maignan, but were put off by the Italian club's £25million asking price. This may look like a foolish move now.
Cole Palmer was hauled off as a result of the red card
|GETTY
Selling Djordje Petrovic to Bournemouth, recouping the £25million that would have been needed for a possible Maignan deal, also seems a rash decision.
Where every other position in the Chelsea squad has been surgically improved and bolstered, their shot-stopping options have remained minimal. Sanchez may have made one mistake too many now, though.
Maresca's frustration, along with Cole Palmer and the rest of the squad, was palpable. It will be difficult for Sanchez to recover from this one, and the club will undoubtedly be looking at other options. It could even be as early as January.
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This was Ruben Amorim's 'Get out of jail free' card
Ruben Amorim has won just nine Premier League games in charge of Manchester United
|REUTERS
There's no denying it; this was a monumental victory for Amorim and United. Their start to the campaign has left a lot to be desired, winning just once prior to today.
But the victory cannot paper over the cracks - there are still huge issues with this squad.
Both of United's goals came from defensive howlers from a Chelsea perspective, a direct result of the red card and three subsequent substitutions that wreaked havoc among their back line.
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It was a game that, particularly given the circumstances, United had to win, and they did win. But fans are no closer to seeing a totally coherent team.
After Casemiro's dismissal evened the teams, Chelsea grew to be the dominant side and even got a goal back to make the final 10 minutes very anxious for everyone in Old Trafford.
Holes in the midfield, nervy in possession and not particularly threatening when going forward; Amorim still has plenty of food for thought.
Having said that, the result is the only thing that matters and United made sure to get on the right end of it. Ending Chelsea's unbeaten league start to the campaign while grabbing their second win is the only thing that really matters.
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Casemiro's ill-discipline could have cost his place in the side
Casemiro's red card could prove costly
|REUTERS
It was a game totally defined by both red cards, so it is only right to discuss them both in length.
Casemiro's second yellow, though arguably a little harsh, was his fourth for United, and his third in the Premier League - this one could also be very costly.
There have been murmurs of discontent throughout the United circle for a little while now regarding 20-year-old Kobbie Mainoo's minutes, or lack of them.
While Amorim has previously claimed that Mainoo is fighting for a spot with Fernandes rather than Casemiro, the Brazilian's red card could have disastrous repercussions for him if Mainoo is given the opportunity he rightfully deserves.
During last week's derby defeat at the Etihad, Mainoo was afforded around 30 minutes on the pitch, and he impressed.
Manuel Ugarte, who seems to be fighting with Casemiro to be Amorim's preferred choice as the second midfielder next to Fernandes, has struggled this season.
He has looked slow and off the pace, while Mainoo, when given an opportunity, has looked sharp on the ball and industrious off it.
He deserves his chance in the midfield. If Amorim is insistent on playing Fernandes in the deeper role, then he has to give Mainoo a place next to him. If they do that, there is little doubt he would seize it and Casemiro could see his minutes in the squad significantly reduced.
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