Sam Walker will start next week and Ethan Strange is on standby to join the Australian squad after halfback Mitchell Moses suffered a lower-leg injury in the thrilling win over New Zealand in the World Cup opener.
Moses did the damage midway through the first half but played through the pain, with the Eels star eventually forced off a minute into the second half.
“He’s not too good in there,” Walters said.
“We’ll get some scans tomorrow (Friday) for him. Once he cooled down a bit at halftime, he was OK, and then when he cooled down, he felt the injury a bit more.
“It’s not so much his calf, it’s more the side of his leg, so we’ll get some scans and see. But when you come off like that when you’re a halfback or any rugby league player, there’s obviously something a little bit wrong.”
Walker was always going to play the second game against Fiji next Sunday as part of Walters’ rotation plan.
But his options going forward will be tested, with Strange a shadow player who will be promoted into the full squad if Moses is ruled out.
Cameron Munster set up a couple of tries against the Kiwis while Tom Dearden came on for Moses and will start next week.
“Sam will play next week,” Walters said.
“We’ll put Tom at five-eighth so they’ll both get their chance to wear the green and gold together, which will be pretty exciting. They’ve never played together as a six and seven, so that’ll be good.
“At this stage, I’m not sure how we go with the injury (deeper in the tournament), but those are my thoughts at the moment.
“If he’s ruled out for the tournament, then we can bring Ethan in, so we’ll just see how that goes in the next couple of days.”
It’s not the only change, with Roosters skipper James Tedesco to replace Reece Walsh at fullback, while Knights centre Bradman Best will also come into the side after they were rested.
“I thought this week for those guys that played in the grand final, it’s been a big four or five weeks. Those teams that made it through to the grand final have played every week through the finals,” Walters said.
“Normally, you get a week off or maybe two weeks off possibly in that grand final, but they’ve been playing every week.
“So I thought what’s best for Australia is that they have a spell this week and we’ll bring them in next week and they can enjoy getting the Australian jersey back on.”
Walsh has earnt the week off after he dominated in his first match in two months with a spectacular 80m try and an incredible tackle to deny Kalyn Ponga.
He had tears in his eyes during the anthem before kick-off and then had watery eyes after his try as he repeatedly spewed on the Allianz Stadium turf.
“He’s a vomiter, he’s a chucker. People get nicknames, and his nickname’s ‘Chucker’,” his coach said.
“He’s not an endurance athlete, he’s a power athlete, and the amount of running that he did, I think he had some big efforts there a couple of times back-to-back, and we’ve seen him do that before.
“We had to relieve him from his goalkicking, which took an eternity to line that goal up, and then he couldn’t kick it anyway, but he’s all right in there now. He’s pretty happy, and for his first game back in a long period, it was a very good effort.”
Walsh wasn’t the only star for Australia, with Jack Bostock scoring a hat-trick on debut, including a flying effort to put his country in front with five minutes to go.
“He put a stamp on his debut game,” Walters said.
“I don’t think I’ve seen a better debut game from a winger or from any Australian player. He was in everything good about the attack and the defence with his athleticism.
“He should be really proud of his performance tonight.”
Originally published as ‘He’s not too good’: Kevin Walters provides worrying update on Mitch Moses, with changes confirmed for Australia’s next match