Former Premier League referee Dermot Gallagher dissects the flashpoints from the weekend's football.
Liverpool 1-1 Man City
Incident: Liverpool were denied a last-gasp penalty when Jeremy Doku clattered Alexis Mac Allister with a high boot deep in second-half stoppage time.
Dermot says: "From my point of view, it's easy to give the penalty. If you give it, there won't be much talk about it.
"Doku gets the ball, there's no doubt about that - the argument is, does getting the ball negate a penalty?
"Well, we saw at Bournemouth [recently], no.
"VAR is sure Doku gets the ball, he's right, so he decides to go with the on-field decision of no penalty.
"It raises lots of dilemmas, I think there would be less argument if it was given as a penalty. I'm surprised there is a wide split. It's a big, big call. He made the decision based on what he saw."
Incident: John Stones rounded off a perfect training-ground routine from Kevin De Bruyne's clever corner to give Man City a first-half lead - but was Nathan Ake illegally blocking Alexis Mac Allister in the lead up to the goal?
Dermot says: "I think it's a good goal. I was surprised when I saw it - I thought 'where are the defenders?'
"They set up differently, and Ake is just too strong. I'd be surprised if the referee penalised anyone there."
Arsenal 2-1 Brentford
Incident: Brentford boss Thomas Frank felt Kai Havertz should have been sent off before scoring Arsenal's winner for an apparent dive in the final half hour, having already been booked for an elbow earlier in the game.
Havertz was awarded yellow card for a trailing arm on Kristoffer Ajer.
Dermot says: "We've seen lots of these this season. He looks at the ball the whole time, not the player, but Havertz does throw an arm out which catches Ajer in the face.
"You've seen plenty of yellow cards for that offence this season."
Incident: Havertz escapes second yellow for supposedly diving under pressure from Nathan Collins inside the box.
Dermot says: "This is very interesting, this decision. If you look at the referee's angle, he sees the ball go to the right, which gives the indication that Nathan Collins has played the ball.
"You also think Havertz goes over Collins' leg - when you see it from an alternative angle it's not the case. But baring in mind the referee decides no penalty. The VAR has two decisions - is it a penalty? No.
"VAR says no penalty, and he cannot recommend a second yellow card. The only time he can say it's simulation is if the penalty is awarded. There is no halfway house, it's all or nothing.
"I think there is enough contact - if you're going to send a player off for diving it's got to be a clear dive."
Brighton 1-0 Nottingham Forest
Incident: Jakub Moder avoided a 67th-minute red card for a lunging challenge on Neco Williams that only drew a caution.
Dermot says: "I don't know [how the red is not given]. If you look at it, he takes off, both feet in the air. That's the clue.
"Speed, intensity and point of contact - it's dangerous. Red card for me. For whatever reason the referee and VAR did not think it was a sending off, but for me it is."
Aston Villa 0-4 Tottenham
Incident: John McGinn is shown a straight red card for taking out Destiny Udogie.
Dermot says: "Credit to the referee here. Cool, calm and composed. Absolutely spot on.
"McGinn comes from a long way with intensity and speed. He's never ever going to get the ball. What the referee did well was take his time, run it through his head, and then dismiss the player correctly."