In the latest edition of Ref Watch, former Premier League referee Dermot Gallagher assesses the key incidents from Tuesday night's games...
INCIDENT: Luke Shaw lunged in over the ball on Johann Berg Gudmundsson, initiating a counter-attack which saw Robbie Brady scythe Edinson Cavani down on the edge of the box. Referee Kevin Friend booked Brady only to have it rescinded after a lengthy VAR review of both incidents ruled Shaw had committed an offence which saw him booked instead.
DERMOT'S VERDICT: Yellow card for Shaw, meaning Brady 'red' immaterial - correct decision
DERMOT SAYS: "I think it's a foul - so I think the referee should stop the game there - and it's a yellow card as well.
"I think the Brady challenge is a DOGSO offence - it is denying a goalscoring opportunity - and is a red card.
"What I would say is, Stuart Attwell the VAR has done the referee a marvellous service. The procedure was good, followed correctly, and I think they've come to the correct outcome.
"It took a long time, but I think it's a red card offence, because Ben Mee will never get back to cover. Because that is deemed a red card offence, they have to go back and look at the attacking phase, and whether there is an error, and they had to revert back to the foul by Shaw. It was a very, very unusual incident.
"We talk a lot about time, and people say: 'Why don't they take longer to get the correct decision' and they have here."
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INCIDENT: Moments later, Harry Maguire rose at the back post to head in Shaw's cross, but there was more controversy as the effort was chalked off after the United captain was adjudged to have shoved Erik Pieters as he climbed to reach the ball.
DERMOT'S VERDICT: Goal should have stood - incorrect decision
DERMOT SAYS: "I think another day, another ref, that would be a goal. If you're chalking this off, how many of Alan Shearer's goals are you chalking off?
"I thought it was good strength. For me, it's a goal. If I was refereeing that, I wouldn't have given a foul. Would you give a penalty if the defender made that challenge on a forward? The answer is no."
INCIDENT: Burnley players appeal for a late penalty as the ball looks to strike Maguire's arm in a crowded penalty area
DERMOT'S VERDICT: No penalty - correct decision
DERMOT SAYS: "I think this would have been very harsh to give a penalty. There's no doubt the ball strikes his arm, but where he is, through the crowd of players, his arms are up, but they are tucked into his body.
"I think the VAR is right to stay away here. The referee's judgement is no deliberate handball, and I'd go with that."
INCIDENT: Billy Sharp's penalty earned Sheffield United the win, awarded after referee Andy Madley was advised to visit the VAR review monitor having originally played on following what he would later deem Federico Fernandez's handball in the visitors' box.
DERMOT'S VERDICT: Mixed thoughts!
DERMOT SAYS: "I have mixed thoughts on this. When you see the angle behind the goal, it looks as though the defender swipes at the ball with his left hand, and moves it away from the forward.
"Is the defender being fouled? This is why it's such a tough call, because it's such a subjective call. Both players are tussling for the ball, there's no doubt about that.
"This is the dilemma: if the referee doesn't consider it to be a foul, which he didn't, you then default to the next thing: is it a handball?"
INCIDENT: Sharp would later find himself avoiding punishment courtesy of the video assistant, when penalised with only a yellow card for a studs-up challenge on Fabian Schar's ankle in the closing minutes.
DERMOT'S VERDICT: Red card for Sharp - incorrect decision
DERMOT SAYS: "I think this is a red card. I thought it was a nasty challenge at the time, and looking at the replay it's above the ankle, with the studs he comes from a distance and with intensity. I think for whatever reason the referee thought it was a yellow, but the VAR should have referred him to the monitor."