Cardiff - Wales great Neil Jenkins has questioned the "unbelievable" lack of action after fullback Leigh Halfpenny was sent crashing to the turf by Australia's Samu Kerevi.
The Welsh Rugby Union confirmed on Monday that Halfpenny was suffering from concussion and following the mandatory recovery protocols after being forced off seven minutes from time during a 9-6 win over the Wallabies in Cardiff on Saturday.
Kerevi slammed into Halfpenny after the Welshman kicked into touch from inside his own 22.
It appeared to many observers a penalty offence at the very least, particularly as World Rugby has ordered a crackdown on head-high challenges in a bid to reduce incidents of concussion.
Yet referee Ben O'Keeffe took no action at all against Kerevi, with Wales -- who went Halfpenny went off lost a frontline goalkicker -- claiming their first win over Australia when Dan Biggar, the full-back's replacement, landed a penalty three minutes before the finish.
"It's unbelievable, how do you think that's not a penalty?" former Wales fly-half Jenkins, now the team's kicking coach, told WRU TV.
"I'm not quite sure what the rules state at this time, but Leigh is a tough old player who is constantly getting up and playing on and doesn't go down lightly.
"For him to go down and suffer an HIA (head injury assessment), there is certainly some form of head contact.
"The referee didn't think so on the day, so we've just got to get on with it. He will go through his protocols and see where he is later in the week."
Halfpenny was likely to have missed this coming Saturday's match against Tonga in any event, with Wales coach Warren Gatland expected to make wholesale changes to his side.
But that would have been with the aim of having a rested and fit Halfpenny available for the November 24 clash with South Africa at Cardiff's Principality Stadium that will conclude Wales' end of year programme.
This case is not the only one that has led to questions about whether World Rugby's clampdown on dangerous tackling is having the desired effect.
Many pundits were equally stunned by the lack of any action taken against Owen Farrell following the England fly-half's seemingly illegal 'no-arms' tackle on Andre Esterhuizen in the closing seconds of a 12-11 victory over South Africa at Twickenham on November 3.