|Autumn International: Wales v Tonga|
|Venue: Principality Stadium, Cardiff Date: Saturday, 17 November Kick-off: 14:30 GMT|
|Coverage: Live on BBC One, S4C, BBC Radio Wales, Radio Cymru, the BBC Sport website and app.|
A challenge by Australia centre Samu Kerevi that left Leigh Halfpenny with a head injury was "reckless", says Wales head coach Warren Gatland.
The Wales full-back had kicked two penalties in his side's 9-6 win.
But he departed after the 74th-minute incident in which Kerevi's shoulder struck Halfpenny's head in a failed attempt at a charge down.
"I thought it was reckless, I thought it was a penalty and potentially a yellow card," said Gatland.
"He [Kerevi] is going to make contact with him because he has gone to charge the ball down, but he has kept that shoulder in that position.
"I asked whether he could have turned his back or put an arm out to soften the blow.
"I think everyone can make up their own opinion on what they see."
Wales host Tonga in their next game on Saturday but even if Halfpenny passes a head injury assessment, he may be left out as Gatland has suggested he will make a raft of changes.
Match officials reviewed the incident, but decided there was no foul play, sparking another debate about such challenges.
Gatland added: "The hard thing for Leigh is that he has now got to go through the return-to-play protocols.
"We will make sure he is right.
"It is a tough job out there for a referee. If the referee puts his hand up and says he has made a mistake, I am happy enough with that."
Changes to face Tonga
Gatland says ending a 13-match losing streak against the Wallabies has put pressure on the players who will face Tonga.
The head coach is assessing options for the 2019 Six Nations and next autumn's World Cup in Japan.
Halfpenny, dead-leg victim George North and prop Tomas Francis, who suffered a back strain, were Wales' immediate worries after beating Australia.
Gatland will be hoping they at least recover to face South Africa in Wales' final 2018 autumn international seven days after taking on Tonga.
Asked if changes were likely, Gatland replied: "Probably. I think we will make a lot of changes and that is because we feel pretty comfortable with the depth we have created and the competition within the squad.
"We didn't always get that right. When we have made those changes against a tier-two nation, the performance has been poor.
"We have snuck home and won games pretty ugly sometimes.
"We have more strength now and I think the players who take the field next week will give a great account of themselves.
"There is a bit of pressure because the players who take the field next week know they have got to go out and perform."