Watch Linesman Constantine Hatzidakis Elbow Liverpool Defender Andy Robertson
Liverpool left-back Andy Robertson appeared to get elbowed in the jaw by one of the assistant referees during Sunday's Premier League game against Arsenal.
The incident happened after the half-time whistle had been blown.
Robertson said something to linesman Constantine Hatzidakis, who reacted by raising his right elbow towards the Scot's chin.
Liverpool captain Jordan Henderson was furious and told referee Paul Tierney what he had witnessed.
Robertson was shown a yellow card.
Assistant Referee Constantine Hatzidakis pictured in 2021
IMAGO/Action Plus/John Patrick Fletcher
Hatzidakis returned to the sideline for the second half and fulfilled his duties as normal.
But the PGMOL, the organization in charge of professional referees in England, issued a statement.
It read: "PGMOL is aware of an incident involving assistant referee Constantine Hatzidakis and Liverpool defender Andrew Robertson at half-time during the Liverpool v Arsenal fixture at Anfield.
"We will review the matter in full once the game has concluded."
The game ended as a 2-2 draw after Liverpool fought back from 2-0 down.
