With the scoreline 1-0 to the Premier League side, Billy Sharp bundled home the ball after a bit of pinball in the box from a Blades corner.
But the referee Paul Tierney ruled out the goal and penalised Sharp for a high foot on Wolves midfielder Leandro Dendoncker, much to the striker’s dismay.
Blades boss Paul Heckingbottom said afterwards: “There’s no contact but everything’s a foul now, so I wasn’t surprised that it was ruled out.
“I think if it’s given it’s not ruled out by VAR… it was one of those tight, marginal calls.”
But Keith Hackett, the Sheffield-born former FIFA referee, insists it was the right decision.
“If the ball is above the waist as a football player now you’ve got to play with your head rather than your feet,” he told Football Insider.
“It doesn’t matter about contact. I’ve got a lot of time for Heckingbottom, I think he’s a great manager.
“But the fact he didn’t make contact doesn’t matter. It’s a dangerous act and therefore he has to be penalised. So the referee was right.”
United went on to lose the game 3-0, with second-half goals from Daniel Podence – who scored a brace – and Nelson Semedo sending the Blades out of the cup.
“Everyone can see where the game was lost,” Heckingbottom added.
“We started really, really well, didn't take our opportunities, then at the other end we gave them opportunities and they took them. That was the difference."