Sam Warburton has led criticism of Wales' tackling technique after Tomos Williams and Gareth Thomas both suffered head injuries in the first half of their Six Nations clash with France.
There were worrying scenes inside the first 10 minutes at the Principality Stadium after scrum-half Williams was knocked to the ground by French centre Jonathan Danty and struggled to get to his feet, clearly concussed as he staggered back to join the Welsh defence.
You can read about the horrified reaction of TV viewers here.
While Williams was soon replaced by Kieran Hardy, moments later Thomas also left the field for an HIA after colliding with Antoine Dupont, before returning to pitch and playing on.
Both players were left dazed after tackling their opposite man with their head wrapped on the wrong side, with Williams being hit in the head by Danty's leg before Thomas got a knee to the face from Dupont.
The poor technique did not escape the notice of Warburton, with the former Wales captain saying he was "in disbelief" at the standard of tackling in international rugby.
Watching a replay of the tackles while on punditry duty for the BBC, Warburton said: "That should be a left shoulder tackle. Tomos Williams' head should be on the right hand side of Danty.
"It's the same again for Gareth Thomas, he's hit him with his left shoulder, that needs to be right, his head's on the wrong side.
"Honestly, I'm in disbelief sometimes when I watch international rugby at how many players do not choose the right shoulder, they just favour a shoulder and go with it.
"It's something I think is under-coached. Being able to tackle on both shoulders is like being able to tackle on both hands. It should be a given for every player."
Fellow pundit Martin Johnson was in total agreement with Warburton, with the World Cup winner adding: "That is a textbook how-not-to-tackle. He's put his head across the player.
"The first thing you learn when you tackle is you put your head to the inside of the player."
When asked by Gabby Logan if better tackling technique would lead to a lower number of concussions in the game, Warburton replied: "Poor tackle technique is the source of so many concussions.
"I think tackle technique must be made compulsory. You have to do five minutes of tackle technique a week. You have to learn to tackle or you produce concussions."
Following the half-time discussion, lobby group Progressive Rugby,which is made up of a number of former and current players, as well as medical experts, described the tackle technique as "awful".
The group tweeted: "Just awful tackle technique for both those head injuries. Good debate between pundits. Such a basic."
The head injuries come just a fortnight after scary scenes at Twickenham, when Welsh front row Tomas Francis was seen staggering and holding himself up on his own posts following a clash of heads with teammate Owen Watkin.
Francis initially remained on the pitch after being checked by a medic before being removed to undergo a HIA, which he duly passed before returning to the pitch around 10 minutes later, and played on until he was replaced by Leon Brown in the 56th minute.
But, under World Rugby laws, any player who shows visible signs of balance disturbance/ataxia after a head blow should be removed immediately and permanently from a match without a HIA.
In an open letter to the Welsh Rugby Union, Progressive Rugby described what unfolded as "a clear and flagrant breach of HIA protocol", while Professor John Fairclough, a leading surgeon who previously worked with the WRU, said it would be a "grave mistake" were Francis to be selected for the clash with France.
However, Pivac defended his selection of Francis ahead of the France game, saying the front row had been approved to play by the Welsh medical team.
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