The Red Devils ultimately got Paris Saint-Germain, in a mouthwatering clash involving Cristiano Ronaldo and Lionel Messi, but the draw has been declared void after a gaffe by UEFA meant United were not in the pot to face Atletico Madrid.
The controversy began when United were drawn against Villarreal, a tie which wasn't possible because the two sides qualified from the same group.
Amid confusion over why the Red Devils were put in the pot to face the Spanish club, Manchester City were subsequently pulled out instead.
And in viral videos on Twitter, it emerged that United were then not placed the pot for a potential tie with Atletico Madrid, who ended up drawing Bayern Munich.
It also became clear Liverpool were mistakenly put in the pot for that tie instead.
Atletico contacted UEFA, who have now confirmed the draw will be entirely redone at 2pm UK time.
A statement read: "Following a technical problem with the software of an external service provider that instructs the officials as to which teams are eligible to play each other, a material error occurred in the draw for the UEFA Champions League Round of 16.
"As a result of this, the draw has been declared void and will be entirely redone at 1500 CET."
While that will be welcome news for United, the likes of Chelsea, Liverpool and Manchester City will not be pleased.
The Blues had avoided Bayern Munich, Real Madrid and Ajax to draw Lille, while Liverpool got RB Salzburg and Man City were set to face Villarreal.
Speaking on talkSPORT, ex-Liverpool midifelder Danny Murphy insisted UEFA were left with no choice.
Murphy said: "It has to be redone. Simple as that. I don't understand why they didn't just start again."