Wales have confirmed that Dan Biggar failed a head injury assessment in the win over Australia.
The fly-half will now go through the return to play protocols in order to be cleared to play.
Biggar will have to pass a series of tests to confirm the absence of symptoms of concussion in the next few days.
If all goes well, Biggar can be cleared to play in a week.
Fortunately for Wales, they now have a nine day break until their third pool match against Fiji.
“He failed a HIA and we have to make sure he goes through those protocols,” said Warren Gatland.
“We’ve got to make sure we go through those protocols in the next week.
"He was disappointed to come off.”
Liam Williams latest
There was another concern regarding full-back Liam Williams, who was limping heavily after being scythed down from behind late in the match.
He continued to the end and Gatland was hopeful over his knocks.
“Liam rolled his ankle but he should be okay,” he said.
Wales now travel to Otsu for some recovery before arriving in Oita to take on Fiji on October 9.
“There are some sore bodies there and have said that, with the short turnaround, it was one of the toughest Test matches they’ve played in a long time.
“We’ll need to make sure we recover. We’ve got nine or ten days until our next match.
“We need to use that in the best way we possibly can to freshen up the guys and make sure we a little time.
“It’s nice to have a decent break before our next match against Fiji.”
