LIVERPOOL star Andy Robertson appeared to be elbowed by assistant referee Constantine Hatzidakis during his side's fiery clash with Arsenal.
Referee Paul Tierney then gave the Scot a yellow card for his protestations AFTER blowing up for half-time.
The official was subsequently surrounded by Liverpool players, including a furious Robertson.
And Jamie Carragher, working on commentary for Sky Sports, quickly claimed that an apoplectic Robertson was "elbowed" by the assistant ref.
He tweeted: "Linesman elbow on Robertson!"
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Television replays appear to show Hatzidakis strike the full-back, with the PGMOL since confirming that they will launch an investigation into the incident.
The officials were booed off by the crowd after exchanging stern words with Reds skipper Jordan Henderson, who protested his team-mate's case.
Sky Sports reporter Geoff Shreeves claimed that Robertson was furious as he entered the tunnel, accusing the official of "elbowing him in the throat".
Roy Keane took a dim view of Robertson, however, calling him a "big baby" and telling him to "concentrate on his defending".
The Irishman ranted: "He should be more worried about his defending. 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."
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Refereeing governing body the PGMOL's statement confirmed that they were "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".
It then added that they would "review the incident in full".
Liverpool boss Jurgen Klopp refused to be drawn on what happened, and when asked by Sky Sports what he made of it, said: "Nothing. I know it happened but I didn’t watch it. If it happened the pictures will speak for themselves."
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Gary Neville claimed that the incident was "not that bad".
But Neville's fellow ex-England international Chris Sutton called on Hatzidakis to be banned.
Appearing on BBC 5 Live, he said: "I really don't know what he was thinking. As far as I can see, he has to be banned.
"He will have to sit out a number of games. I can't remember another incident like this. Where is the precedent for these things?"
Arsenal went in at the break leading 2-1, although appeared to be rocking prior to the interval.
Having led 2-0 via goals by Gabriel Martinelli and Gabriel Jesus, Mo Salah pulled one back for the hosts moments after a flashpoint between Granit Xhaka and Trent Alexander-Arnold ignited the crowd.
Following the half-time whistle, Henderson, Diogo Jota and the already-cautioned Alexander-Arnold furiously surrounded referee Tierney.
Liverpool came out fired up after the break, and were awarded a penalty for Rob Holding's foul in the box.
Salah fluffed his lines, however, rolling his spot kick wide of the post.
The Reds did eventually level, thanks to Roberto Firmino's 87th minute header.
This set up a frantic finish with Liverpool somehow failing to find a winner, Salah being denied by Aaron Ramsdale and Ibrahima Konate inexplicably not converting from close range deep into stoppage time.
The 2-2 draw leaves Arsenal six points clear of Manchester City at the top, although Pep Guardiola's side possess a game in hand.
Arsenal will travel to City on April 26 for a huge title showdown at the Etihad.
