Scott McTominay's eighth minute goal proved to be the difference between the two sides.
United may have got the win but they were far from their best at Old Trafford.
So many players were not their usual self, including Marcus Rashford.
The Englishman has looked bereft of confidence in the 2021/22 season.
And his struggles continued as he put in a lacklustre display against Villa.
Rashford has been criticised by many football fans for one moment in particular in the second half.
Mason Greenwood stormed down the right-hand side and had a shot at goal, which was parried by Emiliano Martinez.
Rashford looked as if he had an opportunity to get to the loose ball first but he didn't even try to captalise, allowing Martinez to gather easily.
Now, it's not a certainty that Rashford would have got there first.
But to see him not even try and run for the loose ball was a surprise.
View some of the reaction to the moment below...
Rashford was substituted shortly after and there were some sarcastic cheers in the home end.
The 24-year-old looks so low on confidence at the moment.
He is virtually unplayable on his day but he's not producing anywhere near what he's capable of.
Hopefully he can get back in the groove and show his best stuff again soon.
United will play Middlesbrough at Old Trafford in the fourth round. The game will played on the weekend of February 5/6.News Now - Sport News