Victory came through for Manchester United in the eighth minute Scott McTominay header but Aston Villa will feel hard done by as they were the better side.
Their 50th minute ‘equaliser’ ruled out by a lengthy VAR decision leaving them with a huge sense of injustice.
Ralf Rangnick will have just been happy for the win, achieved without Cristaino Ronaldo who had a hip injury, although there was now discernible difference either way in performance due to his absence.
This was gritty, but not great.
Still the 12 times winners of the competition are into the next round and a home meeting with Middlesbrough that should open the door to the fifth round.
United began the game on the front foot and were ahead after only eight minutes through McFred.
The much maligned midfield twosome combined to good effect as Fred delivered a superb inswinging cross with his left foot and McTominay added the nod it needed to help it in.
Yet from that moment on to the break it was Aston Villa who were on top and wondering how they weren’t level by the break.
Manager Steven Gerrard had turned and stared down the Stretford End when he got a predictable welcome when he came out and his team were not deterred by the Old Trafford crowd and experience either as they piled on the pressure.
From Douglas Luiz corner, Victor Lindelof almost provided an unwanted assist by nodding it on and Ollie Watkins just could not reach it at the far post.
Emiliano Buendia’s run and cross shot just needed a touch too but Danny Ings could not reach it.
Jack McGinn’s long range effort was palmed away by David De Gea.
Then when Lindelof failed to control a long punt forward by Tyrone Mings, Watkins was in. He turned back inside the retreating United defence and released a shot that crashed off the post with De Gea beaten.
United were rattled but at least got back in the game just before the break with long range shots from Luke Shaw and McTominay reminding Villa that they still possessed their own threat.
It was a good first half between two strong sides.
They both wanted this and five minutes after the interval Villa thought they were level.
McGinn delivered an inswinging free kick which Ezri Konsa headed back across goal with the ball going in off Ings.
It was eventually ruled out, but it wasn’t clear whether it was offside, handball or a foul by Jacob Ramsey on Edinson Cavani.
In the end it was the latter but the fans in the stadium were non the wiser.
Villa’s sense of injustice was compounded when the flag went up to deny them shortly after play was restarted when this time Ings was rightly adjudged to be offside when he broke through before feeding Watkins who side footed home.
The visitors were not giving up and Matthew Cash’s thunderous shot to the near top corner was turned away by the ever alert De Gea.
United responded but when Marcus Rashford had a shot spilled there was no effort from Rashford to leap on the loose ball ahead of goalkeeper Emiliano Martinez much to the annoyance of the Stretford End.
Still United held out as the game petered out.
A huge banner above the tunnel was unfurled before kick-off with images of Bryan Robson, Eric Cantona and Roy Keane with the word ‘Standards’.
They are nowhere near those demanded by this club and these fans.
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