Wales were once again facing a 14-man side for their second consecutive Six Nations match after Scotland prop Zander Fagerson was red carded.
The Scottish forward caught Wyn Jones in the head from distance with a clearout in an incident which was referred to TMO Karl Dickson.
After analysing the 53rd-minute incident, the movement of Wyn Jones upwards was deemed not enough to provide any mitigating circumstances.
Referee Matthew Carley could be heard saying: “We believe the player is clearly at fault and he runs from a distance and has a clear line of sight of the player [Jones].
“We need to know if there’s any mitigation and the point of contact please.”
TMO Dickson responded by saying: “Matthew it’s direct contact to the head, however the player moves his body upwards.”
But the movement was deemed not to be a significant matter, with Carley adding: “We’ve got direct contact and hitting the shoulder directly onto the head.”
Giving Glasgow Warriors’ Fagerson his marching orders as the game entered its final quarter, the referee said: “You’ve had a clear line of sight and you’ve hit him directly in the head.”
Former Wales and Lions captain Sam Warburton is just one who was unconvinced that the action deemed a sending off.
Commentating for BBC, he said: “I think that’s harsh if you’re going to give him a red card.
“Wyn Jones is a threat, he can pick that ball up legally. Because he’s tucked his elbow it doesn’t look as good.
“I do feel for Zander because he has to get rid of Wyn Jones.”
Former Wales internationals Dafydd James and Mark Ring were also among those to question the decision.
But many other fans argued it was a clear red card, with World Rugby looking to clamp down in a bid to increase player safety.
Scotland were leading Wales 17-15 when they had their man sent off, but the visitors responded just moments later with a try to take the lead.
It’s the second successive match where Wales have been battling a 14-man side, with Peter O’Mahony having been sent off in the clash against Ireland in round one after making contact with the head of Tomas Francis.