Michael Cheika has given his support to new concussion rules which allows doctors to intervene and remove players in games.
Tatafu Polota-Nau will not feature against the Blues this weekend as he recovers from a knock to the head.
It follows Kurtley Beale being removed by ARU doctor Warren McDonald in a game against the Rebels earlier this season, as medical staff were given new powers to try to protect injured players.
"They're learning how to use that. It's only relatively knew," explained Cheika.
"They're always going to err on the side of caution and that's normal.
"As they learn to use it and get some consistency amongst the doctors on what they see, it'll be fine because then they can explain it to the coaches.
"We have always just gone off what the player says," he added.
"Everyone else in their whole concussion debate, it's almost like they've put in lots of rules because they think the coaches don't care.
"But it's the absolute opposite. The players are our biggest asset so why would we go out and risk them?
"Taf wasn't feeling 100 per cent after training the other day so there was no question.
"We could have in fact let him hang on until Thursday and see how he went, but we've got to back our other guys.
"We've got a bye next week so he'll be back for sure the week after."