Manchester United beat Wolverhampton Wanderers 1-0 at Old Trafford on Monday night, but it could have been very different for the visitors, who had a penalty appeal against André Onana turned down by the referee and the VAR in injury time.
How could it be that Wolves weren't awarded a spot kick, and what happened?
Read Monday's VAR Review: Should Liverpool have been awarded a penalty for handball by Chelsea's Nicolas Jackson? Why offsides should be getting a bit quicker, as seen in Newcastle United vs. Aston Villa. Plus all the rest of the drama from the opening weekend of the season.
Possible penalty: Foul by Onana on Kalajdzic
What happened: Wolves were trailing 1-0 in the sixth of seven added minutes. Pedro Neto swung in a cross from the right flank that Craig Dawson and Sasa Kalajdzic jumped to meet, with Onana rushing out to challenge. The United goalkeeper clattered into Kalajdzic, but referee Simon Hooper ignored claims for a penalty and the ball eventually went out for a goal kick. The VAR, Michael Salisbury, checked for a spot kick.
VAR decision: No penalty.
VAR review: As the clock ticked down to the end of the match, it had been fairly uneventful for the officials. Bar a handball shout against Nélson Semedo, who had his arms into his body, and a missed yellow card for a foul by Aaron Wan-Bissaka, there was little to report.
Then, deep into the stoppage time, came the incident that changed the complexion of the whole weekend. It was the kind of error that causes PGMOL, the body that runs refereeing in English football, major issues and sets back its attempts to show the organisation is changing.
Jon Moss, the direct manager of Premier League referees, was at Old Trafford. As soon as the final whistle was blown, he went to the Wolves' dressing room to talk to Wolves boss Gary O'Neil and admit there had been a mistake. Howard Webb, the chief refereeing officer, also spoke to O'Neil personally to acknowledge the mistake.
Unlike under the previous regime at PGMOL, the error is acknowledged and action will be taken. Webb and his team have to wrestle with this, as such openness gives the impression of greater mistakes. Figures from the independent key match incidents panel indicate standards are improving, with errors significantly reduced in the second half of last season. But people remember the bad decisions, not the good.
With the high bar for intervention in the Premier League, it's even more important that a VAR is able to identify when the referee hasn't seen what he thinks he has. Otherwise there is too much weight on the on-field decision, and that strangles the purpose of the VAR.
When a check begins, the referee will describe the incident. So, if Hooper says he felt the goalkeeper didn't quite get there and it was a coming together, there's a base for the VAR to begin with. It's then about recognising that description is no more than a loose fit. There has been a coming together, of sorts, but the way that Onana goes into his opponent clearly should be judged as a foul and a penalty kick.
Last season, Leeds United were denied a penalty at Wolves when goalkeeper José Sá caught the head of Rasmus Kristensen after the attacker had nodded the ball back across the area. Although Sá caught Kristensen with his glove, it was at least a genuine attempt to reach for the ball, with no penalty awarded.
Onana jumped through the air with box hands up in starfish fashion, presumably intending to block a header. However, he didn't get anywhere near the ball, or the man who did head it (Dawson) and instead took out Kalajdzic with both arms and pulled him down to the ground.
Salisbury was the VAR for the Tottenham Hotspur vs. Brighton & Hove Albion game in April that had five contentious incidents; the independent panel ruled that there were three mistakes, but only one was a clear and obvious error not picked up by the VAR (the other two were referee mistakes.) Salisbury also missed handball offences for two West Ham goals against Fulham.
The new-look PGMOL is striving for accountability. Salisbury, Hooper and assistant VAR Richard West have been taken off duty for this coming weekend. This, of course, will be of no comfort to Wolves.
After the Brighton error, Salisbury was removed for the next matchweek, and wasn't given another VAR appointment for 3½ weeks.
Although there will always be mistakes -- it's impossible to completely remove them from human decision-making -- it's these egregious errors that have to be eliminated: in added time at a Big Six club against the away team, who would have had the chance to claim a point. It feeds the narrative that smaller teams don't get these decisions.
Despite the huge amount of work being done behind the scenes by Webb and his team, it was always going to be a long-term project to drive up standards; no matter how many coaches you appoint or training days you hold, it all comes back to good decision-making, on the field and in the VAR hub.
At the time of the incident, the Premier League Match Centre, which gives feedback on incidents during games, said the view was that it wasn't a clear and obvious error by the referee. It didn't come with much conviction.
"Jon Moss said it was a blatant penalty and should have been given -- fair play to him, he apologised," O'Neil said after the game. "But fair play to Jon for coming out and saying it was a clear and obvious error -- he couldn't believe the on-field referee didn't give it and can't believe VAR [video assistant referee] didn't intervene.
Gary O'Neil says PGMOL's Jonathan Moss admitted Wolves should have had a penalty after André Onana crashed into Sasa Kalajdzic.
"It probably made me feel worse, actually, because you know you are right. I feel worse about leaving with nothing. Live, I was told they didn't think it was a clear and obvious error."
In May, Webb fronted a pilot show where the audio between the VAR and the referee was broadcast. This will be rolled out on a monthly basis this season, with the first taking place in September, and it's vital that situations such as this are included if the move towards greater transparency and openness is to be underpinned. Fans want to hear what went wrong on the biggest contentious decisions rather than just the discussion around standard VAR interventions.
Information provided by the Premier League and PGMOL was used in this story.