Mo'unga, dumped on the sideline in a big tackle during the 36-0 thrashing, hasn't played since but has been named to navigate the All Blacks around Yokohama Stadium against the Springboks in his nation's World Cup opener on Saturday.
"I was in a lot of pain," Mo'unga said of his AC joint injury.
"It was really tough over the next couple of days to move it or do anything, really. For me to be here, I'm just really grateful and proud of the medical team and rehab that I've done to be in a position to run out for the first game.
"I trusted in what the doctor and physios were saying. They told me I would be sweet, although I didn't feel sweet and thought 'this is going to be tough'. I had to trust them and go along with the plan.
"Obviously there are a lot of boys who aren't here who wished they were. Being really positive in the way of mental health and making sure you do have a plan if things don't work out was really important. I had one of those as well but thankfully for me I'm here and I'm really grateful."
Mo'unga (25) has played only 12 tests after making his debut last year but has quickly become well known for his relaxed attitude and confidence in ordering much older and experience players around the pitch.
"When you are wearing the No 10 jersey for the All Blacks it's part of your role," he said. "It's something you have to do and it's something your team needs you to do. For me it's being as clear as I can with the gameplan and what we're trying to achieve so I can boss the boys around.
"I'll soak it up," Mo'unga said of the expected atmosphere at the ground a day after the opening game between Japan and Russia in Tokyo.
"I'll be out in the middle of the field thinking 'wow, what an amazing time to be here', but knowing in the back of my head I have a job to do and that the team needs me to do my role well."
Midfielder Ryan Crotty, named to start alongside Anton Lienert-Brown, is also returning from injury – in his case a broken thumb - although he had an excellent comeback match for Canterbury then a solid 65 minutes against Tonga. Like Mo'unga, this is Crotty's first World Cup but it's been a long time coming for the 30-year-old.
"Like Richie said, I'm really grateful for the diligence of the medical team and trainers who have helped me. I'm just really lucky to have quality people around me giving me the best advice."
Bridge, like Mo'unga and Crotty a key Crusaders player this season on their run to their third consecutive title, has been named on the left wing in easily the biggest game of his career.
He said he was sitting with teammate Sevu Reece recently in Tokyo with a game from the last World Cup playing on a television nearby.
"We just took a wee moment and thought 'we're at a World Cup. It's pretty crazy that we're here'," Bridge said. "We're both really excited and happy to get a good opportunity this weekend to kick things off."
All Blacks team to face the Springboks:
15. Beauden Barrett, 14. Sevu Reece, 13. Anton Lienert-Brown, 12. Ryan Crotty, 11. George Bridge, 10. Richie Mo'unga, 9. Aaron Smith, 8. Kieran Read (c), 7. Sam Cane, 6. Ardie Savea, 5. Sam Whitelock, 4. Scott Barrett, 3. Nepo Laulala, 2. Dane Coles, 1. Joe Moody. Reserves: 16. Codie Taylor, 17. Ofa Tuungafasi, 18. Angus Ta'avao, 19. Patrick Tuipulotu, 20. Shannon Frizell, 21. TJ Perenara, 22. Sonny Bill Williams, 23. Ben Smith.