Liverpool's third goal against West Ham United showed how far the Premier League has fallen behind by not introducing video assistant referees.
Of course, the assistant referee should have seen that Sadio Mane was offside. It is not even a close call, and we should be thankful that the final score was 4-0 and that the error did not impact the result.
It is a comfortable decision which you would expect an elite assistant referee to get right 10 times out of 10.
However, he is a human being, and human beings do see things differently and they do lose concentration.
It is a difficult job, but we saw in the World Cup how it is possible to make these decisions easier for the assistants.
What they introduced in Russia was a system where, if there was any doubt over an offside decision, the assistant would hold down his flag, safe in the knowledge that it can always be reviewed.
This brought about great accuracy in offside decisions, and it just proves that Mane's goal could so easily have been correctly ruled out.
In voting to extend trials for another year, and not implementing VAR this season, the Premier League clubs are doing a disservice to the game. On this first weekend of the new campaign, there have been a number of occasions where VAR would have helped the referee.
We saw it in the Arsenal v Manchester City game, when Benjamin Mendy grabbed Shkodran Mustafi around the neck in the penalty area. It was a clear penalty, and there is a danger here of allowing players to escalate again the holding, pulling and grappling in the box.
The reason we had such a high number of penalties during the World Cup was because VAR brought these incidents to the attention of the referee.
It is doubly frustrating because we saw this weekend how easily technology can help the game.
Jan Vertonghen's goal for Tottenham Hotspur against Newcastle United crossed the line by just 9mm, and without goal-line technology would never have been given.
We waited years to introduce goal-line technology - nobody screams about that now.
The other pressing issue from this opening weekend was the continued failure of referees to properly punish simulation.
Brighton's Anthony Knockaert was correctly denied a penalty when he went down too easily against Watford, but why did the referee not stop the game and issue a yellow card? The player essentially got away with simulation, so there is no deterrent for the future.
So much was made of the introduction last season of a panel that reviews footage each Monday and tries to identify cases of simulation.
But, despite the fanfare, it so often failed to show its teeth last year. Referees are failing to show a yellow card when a player has gone to ground in search of a penalty, and we saw this frequently during the World Cup, too.
The only way we are going to deal with the problem is with retrospective punishment.
Every time a player gets away with simulation, it is making life even more difficult for grass-roots referees in the local park, because the truth is that kids will always try to emulate the stars. (© Daily Telegraph, London)
Keith Hackett is a former referee and resident expert for You Are The Ref.Com
Telegraph Media Group Limited 
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