Injured Wallabies captain Stephen Moore says Mann-Rea has the resolve to perform on the international stage, as the rake known as "Bongo" contemplates the biggest moment of his career.

Mann-Rea is on standby for a surprise bench spot for the Test against South Africa in Perth, while back-up hooker Saia Fainga'a waits on the birth of his child.

If Fainga'a has to fly home to be with his partner, Mann-Rea, 33, will be thrust into the Wallabies jersey less than two years after he was preparing to retire.

The Wallabies' hooker crisis has already claimed skipper Moore, Tatafu Polota-Nau and Nathan Charles. But the growing injury toll has opened the door for Mann-Rea to cap a remarkable journey from the rugby scrap heap and the Wollongong coalmines to a dream Wallabies jersey.

"These things come around when you least expect it," said Brumbies and Wallabies captain Moore.

"If he gets a chance he certainly won't let anyone down. It's well documented he's seen this as a second chance in his rugby career and there's no one in our squad who works harder than him. His form for the Brumbies [at the end of the year] was a really good indicator of his capability. The hooker injuries are unbelievable, it's always the way that when you get one, you get a couple."

Mann-Rea was tasked with leading the Brumbies' set-piece in July when Moore (knee) and Siliva Siliva (knee and ankle) had season-ending operations. But the journeyman front-rower was hampered by a torn hamstring, which he suffered in a club rugby game for Gungahlin.

Knowing he was the only fit hooker left at the Brumbies, Mann-Rea played three games with a busted hamstring and pushed through agony to help the franchise reach the semi-finals.

"You remember that sort of character in your teammates, he pushed through because he knew there was no one else, and everyone respected that," Moore said. "That sort of effort shows someone like Ewen that [Mann-Rea's] got the resolve to operate in the Test environment, he won't let anyone down."

Mann-Rea was considering retirement again this season, but he signed a one-year extension to prolong his Super Rugby career. The hard-nosed veteran started his career with Moore in the Queensland Academy and played in junior Australian teams with Matt Giteau and Mark Gerrard.

But Mann-Rea admits he threw his chances away and his career was at the crossroads when he was working in the Wollongong coalmines. An offer from a Japanese club helped him resurrect his career before he signed a one-year deal with the NSW Waratahs in 2011.

He broke his thumb and was ready to retire when the Brumbies offered him a "lifeline" chance and Mann-Rea has not turned back.

Mann-Rea started on a $40,000 extended-squad deal in Canberra but has earned a place in the Brumbies' full-time.

"Two years ago there's no way I thought I would be here," Mann-Rea said in July. "After Japan, for a while I thought footy was over. I got a lifeline to the Waratahs when [hooker Damien] Fitzpatrick got injured, then I broke my thumb and I thought it was gone again ... Not many guys get a second chance at my age."