New Zealand will be without Ryan Crotty for the second Test of the Bledisloe Cup in Auckland next week after the centre suffered a concussion on Saturday, while Australia have lost the services of Israel Folau due to a muscle injury.
Crotty was knocked out after making accidental contact with debutant team-mate Jack Goodhue as the All Blacks defeated the Wallabies 38-13 in Sydney.
The 29-year-old, who had made 38 appearances for his country, has now sustained six concussions in the last 20 months.
"It concerns us, definitely," All Blacks coach Steve Hansen said.
"He's already seen a specialist and they've given him the all-clear. From our understanding as long as you fully recover and don't go back when you're not fully recovered, then you're OK.
"He was just unlucky last night. It was freaky – friendly fire from Jack straight in the face. It would have knocked most of us out."
Team-mate Sam Cane added: "It's not nice to see. It's just a tough injury. Everything else has a time-frame but there's just so much unknown with head knocks and it seems like you can be only one away, if it's the wrong one, from it being then end of it.
"I've seen that with a few mates. It certainly helps you appreciate every week and every game you have and realising how fickle it can be."
Australia, meanwhile, will be without star fullback Folau for at least the next match.
"He's just got a small tear in a muscle right down low. Quite rare really," Wallabies coach Michael Cheika said.
"But it's actually not a long-term injury at all, just a lot of swelling."
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