A captain's performance
All eyes were on Zaha in the Crystal Palace lineup: captaining his club for the first time in a competitive appearance at the ground of his former side, where he made just two first-team appearances.
And how the viewers were rewarded. A battling performance that is not often associated with wingers who have been adapted into strikers. He got the better of Victor Lindelof time and again before ultimately providing two decisive goals.
Stepping up to take the second penalty after Jordan Ayew had missed it, he showed his nerve to dispatch his shot high past David de Gea, a player who would have been running high on confidence and fume (perhaps rightfully so).
He was consistently on for the counter, forcing United back and getting defenders turning towards their own goal and running - the one thing they hate to do.
His second and Palace's third lead to big celebrations down on the flank, and with no crowd in attendance you could really appreciate the joy Zaha was exuding.
The Palace star has had more than his fair share of critics doubting whether he could make the step up to a top-four team after his experience at United, and putting two goals past them must be a hell of a feeling for the 27-year-old.
Strong defensive performance despite missing personnel
Scott Dann was one more name added to Roy Hodgson's defensive injury list, forcing his hand with the inclusion of Mamadou Sakho in the starting line up.
Hodgson admitted after Sakho's substitute appearance in midweek against Bournemouth that the medical team weren't too keen on the defender playing, but he was convinced by a conversation with the France international.
And the defender looked like he'd never been away. Obviously it will take some time to get fully up to match speed, and adrenaline will play its part in a performance like this.
But it was refreshing to see how coolly Sakho dealt with the threat from United, a notoriously pacey team who can pull the opposition into difficult areas.
Alongside him, Cheikhou Kouyate continues to impress in the centre of defence. United's goal did ultimately come from his mistake, a mis-kick that landed at the feet of Donny van de Beek.
But to distil his performance down to that single moment would do a disservice to the 80 minutes that came before it.
Kouyate saw danger before it happened, whipping the ball away from Anthony Martial in one notable second-half moment.
Joel Ward put in a fine performance, rarely putting a foot wrong as United did most of their attacking down the left in the second half.
And Tyrick Mitchell: what a start he's had to his Palace career. The left-back marked Daniel James out of the game in the first half, with the winger being substituted after 45 minutes.
And though Mason Greenwood offered a different threat cutting in from wide, Mitchell rarely looked too troubled.
Maybe it had to do with United's bluntness and failure to really launch much in the way of overlapping attacks until around the hour mark, but Mitchell was receiving instruction and praise throughout from the Palace bench.
Townsend's importance
A lot of fans will have been hoping to see Eberechi Eze start, and rightfully so: he's a top young talent and the club's new signing.
One of the spots he could have taken is that of Andros Townsend, but the 29-year-old put in another performance that shows his importance to the side.
His link-up play with Wilfried Zaha was extremely important for this Palace side, particularly in the second half when the chances to counter were going begging.
He obviously showed his eye for goal with the opener, but he performed with distinction throughout, both in setting attacks and preventing them.
VAR Controversy - again
The handball was slightly iffy. The type of call that you'd simply hate to get against you. There was not much
Lindelof could have done to avoid giving away that penalty - other than try and tackle Ayew before, of course.
But United can probably count themselves a little unlucky with the re-take decision. Yes, De Gea was off his line - slightly. I know - rules are rules. But to punish someone so severely for such a minor infraction - especially when you consider the stuttered run ups that players are allowed to use, it feels a little unsportsmanlike.
Palace fans probably won't be complaining about the decision this time, but it's a warning that it can happen to anyone, and it's not something that's really in the spirit of football.
