In the latest Ref Watch, former Premier League referee Dermot Gallagher runs the rule over the big incidents of the weekend, with Raheem Sterling at the heart of the action.
INCIDENT: Raheem Sterling catches Timo Werner with a lunging tackle. VAR takes a closer look but officials at Stockley Park decide against upgrading his yellow card to a red. Should he have been sent off?
DERMOT SAYS: "I think not. It's not a good tackle but he's one-footed, he's low, he doesn't travel too far.
"It's a high-tariff yellow card but I wouldn't expect him to be sent off for that."
INCIDENT: Sterling later goes down in the box under Kurt Zouma's challenge but VAR judges the defender not to have fouled the England international. It proved a crucial decision as Chelsea broke clear at the other end and wrapped up victory.
DERMOT SAYS: "If the referee gives a penalty on the field, I'd say, 'Clumsy,' and we'd move on. Because the ref doesn't give a penalty, that's why we're talking about it.
"It's the safer option to give a penalty for that. I can't explain it. Zouma is clumsy, doesn't get the ball and I think it's a penalty. Once Anthony Taylor decides it's not a penalty, VAR can't say it's a clear and obvious error.
"If the penalty had been given, the VAR wouldn't have overturned it. However you cut it, this is an on-field decision."
INCIDENT: Manchester City are awarded an earlier penalty when Billy Gilmour upends Gabriel Jesus - but Sergio Aguero fluffs his Panenka...
DERMOT SAYS: "You have to look at each penalty incident individually. I think this is a penalty. Jesus pushes the ball one way, tries to protect the ball with his body, and Gilmour catches him."
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INCIDENT: Douglas Luiz is punished for tripping Paul Pogba in the box - a decision called "pathetic" by Aston Villa boss Dean Smith.
DERMOT SAYS: "Can I understand Dean Smith's frustration? A little bit. Yes, I think it is a penalty. Chris Kavanagh has got the perfect view. Luiz quite clearly catches Pogba in the back of the legs.
"We talked about Sterling earlier - Zouma caught him in the back of the legs and I thought it was a penalty so I can't say that's not a penalty. If you ask for consistency, I think all three [Zouma, Gilmour, Luiz] are penalties."
INCIDENT: Smith's ire is further compounded as Ollie Watkins is booked for simulation - the second yellow card drawing a red one - after a battle for the ball with Dean Henderson.
DERMOT SAYS: "I think one of the secrets of refereeing is to retain options and in this situation, there's three options.
"Is it a penalty? I think not, there's minimal contact. Is it a dive? For me, no. The third option is to do nothing and I think if the referee had just pointed for a goal-kick, some people would have thought penalty, some people would have thought dive but people would have accepted that it wasn't a red card for a dive. That was the safest option for me.
"I do think there is a bit of contact, but I don't think he dives. I think he is very unlucky and if the referee looks back at what I've seen now, which he couldn't on the day, he may well have made a different decision.
INCIDENT: Should Villa have had a penalty of their own when the ball catches Mason Greenwood on the arm?
DERMOT SAYS: "Proximity to the ball, certainly. You see him jump with his arms up, the ball comes off Douglas Luiz and he's so close [to the ball], he's got no chance to get out of the way.
"His arm is up - but is it up to go towards the ball? I think not. He's taking his arm away. Play on was the correct decision and the VAR agreed."