The PGMOL confirms it is investigating after assistant referee Constantine Hatzidakis was caught on camera appearing to elbow Liverpool defender Andy Robertson at half-time of his team's match against Arsenal on Sunday afternoon. The Reds were locked in a spectacular tussle with The Gunners at Anfield when the bizarre incident somewhat stole the show. Ad After the whistle had blown to end the opening 45 minutes with Arsenal 2-1 to the good, Robertson approached the assistant referee and received an elbow to the throat.