The Boro were then faultless in the penalty shootout and in front of the Stretford End pulled off the unimaginable and progressed to the fifth round of the FA Cup.
Wilder: The Cup is alive and kicking!
To say the Boro boss was delighted would be an understatement: "The FA Cup is alive and kicking, especially in Middlesbrough. I told the players it was all about making memories.
"We rode our luck and took our chances. The decisions that are made through VAR have changed since I left the Premier League - I thought straight away it was handball. I thought it would be chalked out and delighted it wasn't."
Wilder went on to praise his squad's belief: "You saw tonight we've got plenty of character and bottle in there which you need.
"We were delighted to take it deep. To take it to penalties is no mean feat for us against the likes of Manchester United.
"When their team sheet come out, you see straight away how much they respect the competition and us. That was a really strong Manchester United side out there.
"We rode our luck at times, as you have to. You always understand that when you come here, and they've got the players they have on show, they're always going to create a lot of chances.
"I was delighted we were only 1-0 down at half time and then it was a different Boro side second half and we hung on in there," he added.
For the Boro, they have progressed to the next round and may the magic of the cup be with them.