The PGMOL have said they will investigate an incident involving Liverpool defender Andy Robertson and assistant referee Constantine Hatzidakis in the Reds' 2-2 draw against Arsenal in the Premier League on Sunday.
Robertson appeared to be caught in the face by an elbow from the assistant as he remonstrated with the official at the end of the first half at Anfield.
"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," the Premier League's refereeing body said in a statement after the game.
"We will review the matter in full once the game has concluded."
However, Robertson looked to have made contact first with the assistant and Roy Keane had no sympathy for the Scotland defender.
"He should be more worried about his defending," the former Manchester United midfielder told Sky Sports at half-time.
"Do you know what he is? That Robertson, I've watched him a number of times. He’s a big baby. That's what that guy is."