Refereeing body PGMOL will investigate after Liverpool’s Andy Robertson appeared to be elbowed in the chin by assistant referee Constantine Hatzidakis.

Robertson approached the official angrily at the end of the first half against Arsenal and appeared to shove him as he passed, with Hatzidakis raising an elbow which hit Robertson.

The Scot reacted furiously and, along with several team-mates, approached referee Paul Tierney, who booked 29-year-old Robertson.