Rangers should have had a penalty when Liam Scales fouled Vaclav Cerny, according to the IFAB laws used to govern the game.
The Celtic defender began his foul outside the box but footage shows conclusively the pulling continued on the line of the penalty area.
And that means VAR should have intervened and advised John Beaton to come to the monitor to check his initial decision to award a foul at the edge of the box.
Law 12 clearly states: "If a defender starts holding an attacker outside the penalty area and continues holding inside the penalty area, the referee must award a penalty kick."
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Bobby Madden, former top-flight referee and now Instagram pundit took to the platform to air his expert view.
"This is 100 per cent a penalty kick," the ex-Scottish FA whistler wrote on Instagram. "It doesn't matter when the holding started, when it ended or what direction the players are moving.
"This is clear evidence of holding within the penalty area and I'm amazed this hadn't been identified by VAR. Referee team had been excellent until that point. Difficult live, but that's why VAR is there."
