Former ref explains all after assistant referee accused of elbowing Robertson

Liverpool's 2-2 draw with Arsenal was marred by a half-time incident involving home defender Andy Robertson and assistant referee Constantine Hatzidakis.

It has been alleged that Robertson was elbowed by the linesman as the half-time whistle blew. The Liverpool left-back approached the official and footage appeared to show his elbow hitting the defender.

Robertson was given a yellow card by referee Paul Tierney for his role in the incident, while Liverpool captain Jordan Henderson went up to the officials to discuss what had happened.

The Professional Game Match Officials Limited (PGMOL) body, which governs referees in English football, has said it is investigating the incident, as is the Football Association.

Former Premier League referee Dermot Gallagher takes part in a Q&A below about the next stages:

Do you think Constantine Hatzidakis elbowed Andy Robertson?

We don't know what's happened. We are going off what we see and presume.

Only he can answer that. We can only speculate and I'm loathed to do that because of the ramifications it can have for Constantine Hatzidakis, Andy Robertson and football in general.

You look at the different angles, you have to be careful that you don't start speculating and end up thinking and putting yourself in his head, asking why did this and this happen? You have to go through the facts and see what happens.

What are the next steps now the PGMOL and FA are investigating the situation?

What is interesting is that the PGMOL have said they are going to come out and review it. They will speak to the relevant parties. They will be able to speak to Constantine Hatzidakis very quickly as he is one of their members. I'd be stunned if they didn't try to speak to him after the game, as soon as he showered and changed! Time is of the essence, people need to know what has happened. When we have drilled down into that, it's the next stage of the process.

I think, without doubt, the PGMOL and Howard Webb will speak to Hatzidakis, ascertain his view and thoughts and how he feels. The FA have already said they will speak to him and Andy Robertson on Sunday and Monday. It's just a matter of following the process.

Could Paul Tierney have done anything more in this situation?

It's difficult for the referee. For example, if a player comes to me and says 'I've been spat at' - I think that's the most unsavoury thing - but I can't do a lot about it unless I've seen it or one of my officials has seen it. I can't just go on what a player tells me. I have to make people aware. The players made Paul Tierney aware. But we don't know what actually happened in that period.

You know and have worked with Constantine Hatzidakis. What is he like as a referee and person?

He is a really great guy. I'm not just saying that. I remember him when he started out refereeing. He was very young, keen and wanted to learn.

I remember when he came to a game at Millwall training ground and ran the line for me at a reserve match, and after the game he was thirsty for knowledge and asking about what happened in the game.

He went higher up to become a referee for the National League. I had the privilege of watching him and he is a good referee. You don't get to that level without being a seriously good referee.

He had the opportunity because of the pathway to become a referee or an assistant, he chose assistant. And he's gone on from there to become an international assistant. He's at the top of his game - and he's a really nice guy.

Can a referee just snap under big pressure or in front of a big crowd?

I can only speak for myself. I have refereed in some real hostile atmospheres and some really tough games. I have refereed a South American Champions League final in Brazil - it's a tough environment.

But I could never imagine myself in a position where I could lose my composure. When you referee, you have to be in control of yourself. That's the only way you can control the players.

So I'd be stunned if he was in that position. I'm not saying he didn't, but it's alien to how we're brought up as referees.

Is this incident common in football?

I have never seen an incident like this at any level. I've had the misfortune to have read about some of my colleagues who have been part of some unsavoury incidents.

But this is so unusual. It's just a matter of being careful that we don't start to speculate and make your own mind up about what has happened.

Some say Hatzidakis should be dropped for next weekend? Is that the right thing to do?

It depends on the outcome. Without doubt, the PGMOL and FA will want to act swiftly. But there is no point acting swiftly and coming to the wrong conclusion.

They need to get enough time to speak to all parties, gather all evidence and gather witnesses. Then put that together and come to the conclusion. Then you can come to a decision.