Walsh had one of his maverick nights on Thursday that proved why Walters has been reluctant to settle on the Brisbane fullback or James Tedesco as his first-choice No.1.
The Broncos star pulled off a terrific try-saver on opposing number Kalyn Ponga in the first half, before scoring a try for the ages in Australia's 24-22 win over New Zealand that has the Kangaroos on the cusp of claiming top spot in group A.
For just when the Kiwis looked to be gaining the upper hand, Walsh conjured more magic by jinking and jiving past four defenders including Ponga to go 70m to score.
The fullback was so exhausted by his efforts in his first game since coming back from an ankle injury that he had to repeatedly vomit on the Allianz Stadium turf and hand goalkicking duties to centre Latrell Mitchell.
"Two pieces of toast (for a pre-game dinner) will do that for you," Walsh said.
"It's been a while since I've played a game, so it was good to blow the cobwebs off.
"I've been doing it (throwing up) since I was 12 years old, I don't know what it is but every time I do a big run - that's why I took my mouthguard out mid-game - I knew I was going to gag.
"Once I start doing that, it's game over. I don't know if it's nerves or sports science, but if there's anyone out there that can help me, I'll pay top dollar."
Walters labelled Walsh a "chucker" but said he was likely to let Tedesco - as well as Sydney Roosters teammate Sam Walker - loose against Fiji in Brisbane next week.
The battle between Clive Churchill medal winner Tedesco - a former World Cup-winning captain - and Walsh has dominated the build-up to Australia's group stage matches with Walters expected to leave a decision until the knockout stages.
"The first thing he (Tedesco) said to me is, 'Whatever you need to prepare for the week, and I can help you with, I'll do'," Walsh said.
"Being so young to be able to see an ultra competitor like that, if I can take anything out of that, and the way he handled it, it's that he was massive for me this week.
"I can't wait to see him get his opportunity… I might put my hand up to jump on the bench or something."
The only concern for Walters, who is expected to rotate his squad through the group matches, is the fitness of Mitchell Moses.
Without Nathan Cleary, Moses is the Kangaroos' strongest last-tackle kicker but the Parramatta man failed to finish Thursday's narrow win.
Canberra five-eighth Ethan Strange has been on stand-by in the event of an injury.
"If he (Moses) is ruled out for the tournament we can bring Ethan in so we'll just see how that goes the next couple of days," Walters said.
