From bad tackles, to end-to-end action and a red card, the game encapsulated English football and was just a few goals away from being a classic.
It was Chelsea who eventually booked their place in the semi-finals thanks to N'Golo Kante's 51st minute strike - but only after Ander Herrera's careless sending off.
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Despite receiving a yellow card moments earlier, the Spaniard produced another poor challenge on Eden Hazard 10 minutes before half-time and was shown red.
While the scoreline was 0-0 at the time, United were still given a mountain to climb and eventually succumbed to the mounting pressure from Chelsea.
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Were it not for Herrera's moment of stupidity, the Red Devils might have ended up as winners having started the game very brightly.
Jose Mourinho certainly seemed frustrated on the sidelines, with the Portuguese and Antonio Conte coming to blows in the 40th minute.
Fans assumed the pair were arguing over Michael Oliver's decision to dismiss Herrera but, as it turns out, that wasn't the case at all.
Footage has emerged showing exactly why Conte was so angry with Mourinho who, in the video below, kicked the ball at the Italian after Antonio Valencia fouled Marcos Alonso.
Conte then marched over to Mourinho and started shouting at him in an angry rant. Check it out.
MOURINHO KICKS THE BALL AT CONTE...
...CONTE LOSES HIS COOL
Now it all makes sense. Mourinho and Conte didn't shake hands after the game, but United's manager insists it wasn't because of any bad blood between them.
"If I see him (Conte) here, I shake [his hand]," Mourinho said after the game.
"I didn't because I thought my players deserved my action immediately and our supporters also deserve thanks to them, so it was that.
"I can promise you, if I see him there (outside the dressing room) I shake his hand, I have nothing to say to him at all, but to shake his hand, for sure, I will do that."
Mourinho also addressed the abusive chants aimed at him from the Chelsea fans, saying: "The fans can call me what they want.
"I am a professional. I defend my club. Until the moment [Chelsea] have a manager that wins four Premier Leagues for them, I'm the No.1.
"When they have somebody who wins four Premier Leagues for them, I'll be No.2. For this moment, 'Judas' is No1."
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