Ref Hatzidakis crossed big line elbowing Robertson in the face

Andrew Robertson's eyes were wide and blazing, as Mohamed Salah tried to lead him away. He had the kind of look you might expect someone who had just been mugged to sport — the shock, disbelief — as realisation kicked in.

'He's just f***ing elbowed me!' Robertson barked to Salah. His anger would have been plausible had he been cracked on the chin by an opposing player, but by an assistant referee?

Just when you think you have seen it all before in football, along comes something to leave you dumbfounded.

Constantine Hatzidakis had indeed elbowed Robertson, as Liverpool and Arsenal's players headed off at half-time.

We are not talking an elbow with the ferocity of, say, Mark Dennis, Terry Hurlock or Pat Van Den Hauwe levels from the 1980s but there was intent and there was a connection.

Robertson, to be clear, should not have put his own hand on Hatzidakis as he looked to argue a point.

Too many players are overstepping the mark when it comes to confronting officials and the Scotland left back was guilty of making contact with the 38-year-old.

Hatzidakis, though, is in a position of authority. Restraint and remaining neutral and calm under pressure are part of the job description and the moment he glanced over his shoulder and jutted his right elbow backwards at Robertson, he was destined for a raft of headlines and — in all probability — a ban.

Such was the severity of the incident, the PGMOL — who have had another busy and lamentable weekend — took the step of issuing a statement while a spectacular game was unfolding. The FA also made it clear they would be examining the incident.

Quite right. Can you imagine what we would be saying today if a player had done something similar? It was only last month that Aleksandar Mitrovic, the Fulham striker, sparked opprobrium for what he did to Chris Kavanagh at Old Trafford in the FA Cup. He was banned for eight matches.

If this is the benchmark, should Hatzidakis officiate again this season? It is impossible to see how he does. And how, for that matter, could the PGMOL put referee Paul Tierney and his team on a Liverpool game again in the foreseeable future?

There is history in games involving Liverpool and Tierney that goes back to the Tottenham Hotspur Stadium, in December 2021, when Robertson was sent off, Harry Kane avoided a red card for a horrible tackle and Diogo Jota was not given a penalty that for all the world looked a certainty.

To be clear, this is not an excuse for anyone's behaviour. It is simply an explanation of the context around a display from Tierney in which he dealt more cards than an overworked croupier and Hatzidakis put himself into the eye of a storm.

When asked about the incident with the elbow, Klopp said: 'I didn't see it and I now obviously have time to watch it but I didn't just because I cannot give wrong answers. I didn't see it. I heard the pictures speak for themselves. I cannot say more. I didn't see a bit of it.'

Pressed further on some decisions within the game — Liverpool looked to have claims for a second penalty late on, when Salah was tugged by Arsenal defender Gabriel — Klopp paused, turned his head away and tried to think of an answer that wouldn't get him into trouble.

'I think there are some things we can talk about but they are not really helpful,' said Klopp. 'We had our issues with some referees. They don't come to us (to discuss things). We have to go to them (if that is the case) — and we didn't.'

With that, Klopp left. He was gone but that certainly is not the end of things.

Hatzidakis will have an opportunity to give his own version of events — Robertson turned down the chance to speak when he was asked as he left the stadium — but he has made a colossal error.

We are in a period where referees are heading out of the amateur games in droves because of the intimidation they are subjected to each weekend.

It is a slight on the sport that that is the case and they should absolutely be afforded respect for doing an often thankless task.

But let's not kid ourselves that they are all perfect, and Hatzidakis crossed a significant line. He will have to accept the consequences.