The Wallabies and New South Wales Waratahs Super Rugby hooker Tatafu Polota-Nau has been given an additional three weeks to recover from his latest bout of concussion.
Polota-Nau, who has a lengthy history of concussions, has already missed the Waratahs' two most recent matches after suffering a head knock against the Brumbies.
The decision to extend his layoff means he will miss Saturday's grand final rematch with the Crusaders in Sydney and also the team's two matches in South Africa against the Lions and Cheetahs.
"There is no point in taking him to South Africa and having doubts over him," said coach Michael Cheika on Tuesday.
"We'll let him have a few weeks off and get sorted out and he can start again when we come back from South Africa."
Polota-Nau missed two games after a head knock earlier in the season.
The latest schedule would have him returning in the last round home match against the Queensland Reds.
Cheika said Polota-Nau would have been comfortable about playing now and there were no major issues with his recovery.
"We're there for the longer run as well, we're better off just giving him a stretch and (get) fully recovered and go from there," Cheika said.
"He's not showing any symptoms,or anything like that, but that's just the decision we've decided to take."
"There's some big games to come and you want to make sure he's 100 per cent ready for those."
He said backup hooker Tolu Latu was playing great football and putting himself in possible contention for a Wallabies squad berth.
"His performances are putting him in the battle, there's no doubt about it," Cheika said.
"He's got a good-sized frame, he's becoming a strong scrummager."
"He's learning more about the scrum. He's playing first team football at Super Rugby level very well, so he's definitely a contender."
Cheika said he would give flanker Jacques Potgieter until tomorrow to overcome a sternum injury that kept him out of last week's game.
The mystery over the future of powerhouse winger Taqele Naiyaravoro grows following a report he has signed for Glasgow and not their Scottish rival Edinburgh, as had previously been reported.
"Glasgow have been talking to me for a while and opened the door for me, so I'm happy to have signed a long-term contract with the club," he was quoted as saying.
"I'm looking forward to moving to Glasgow with my family to continue my development."
While the reported deal with Edinburgh was believed to have a get-out clause if Naiyaravoro made the Wallabies squad, Cheika had no knowledge of the terms of any deal with Glasgow.
He said he had spoken to Naiyaravoro regularly and that no time frame had been put in place for the player to make a decision.
"I think that we'll just leave it for now and we'll see where he ends up playing footy next year," Cheika said.