Fred was shown a yellow card in confusing circumstances during Manchester United's Champions League tie with PSG.
The United midfielder was involved in an altercation with Leandro Paredes that saw the PSG star hit the deck after Fred moved his head towards the Argentine.
The incident prompted a VAR check for a possible red card due to serious foul play, with Italian referee Daniele Orsato being sent to the pitchside monitor to watch a replay of the incident.
Yet there was confusion when Orsato opted to show Fred a yellow card rather than a red. It was a decision that was in contrast to UEFA chief refereeing officer Roberto Rosetti's view on what VAR should be used for.
In a pre-season interview, Rosetti said VAR will only intervene when it believes that a red card could be warranted.
He said: "The VAR will also intervene when there is evidence of serious foul play, which must be sanctioned with a direct red card in line with the Laws of the Game."
Speaking on BT Sport, former Premier League referee Peter Walton said the decision came down to a matter of opinion.
He said: "I think the referee has looked at it and said it's not a red card in his view. He's looked at it and said it was a yellow for a reckless challenge.
"However, I'll stand by my first opinion that Fred walked a very thin line there. It could have been a red card but the referee has chosen to show a yellow, which I don't think is a mistake but it's his opinion."
