Mo'unga, who played a key role in his Crusders' side's three Super Rugby titles, and who has been entrusted with the starting five-eighths role this year as the side looks for variations to break down opposing defences, said for the younger players in the group, they were guys who loved the game and who were thrilled with the opportunity they had been given.
"You can't under-estimate just how grateful we are. We are just so pleased to be in this environment and to be given this opportunity. We just want to get out there and do our bit," he said.
He said he often joked with starting right wing Sevu Reece about 'who would have believed' at the start of the year that they would be preparing for a World Cup quarterfinal, let alone all Crusaders teammate left wing George Bridge as well.
Mo'unga said Ireland's first five-eighths Johnny Sexton was a world-class player with finesse to his play. He had a lot of good touches, his catch-pass and his kicking game were great.
Mo'unga said his partnership with Beauden Barrett was great. They had come a long way since first being paired earlier in the year and they were still working on their combination.
"It's important to know we're never going to get everything right but we're trying to sharpen up parts in our game so that we can help each other out and, as key drivers of the team, help the team out," he said.
Mo'unga said his contact with Crusaders assistant coach and former Irish and British & Irish Lions five-eighths Ronan O'Gara had shown him how driven and determined the Irish were.
"I know that this week is going to be a very tough test and they are going to come guns blazing," he said.
His earliest memories of Rugby World Cups were the impact of Jonah Lomu.
"He inspired a lot of young Kiwis and I would have no doubt he inspired a lot of the world in terms of rugby. As All Blacks it means a lot to us if we can inspire people and inspire young Kiwis and that was how my love of the game grew. He was able to do things that other people could never do and that inspiration grew within me, grew my love for the game and grew my desire to be an All Black," he said.
Bridge said there had been a lot of work at training this week under high balls because they had to be able to take the anticipated kicks from the Irish.
"We've just got to be pretty confident getting up in the air and winning the aerial battles," he said.
Bridge said while there might not be the number of caps in the backline that there had been in the past, the players concerned didn't feel inexperienced and they were comfortable with how they wanted to play as individuals and as a backline.
"Guys like Aaron [Smith] and Beaudy [Beauden Barrett] do bring a lot of experience but they make us really reliant on being able to perform and we go throughout the week just getting ready for the game. That's all we can do, you can't really look at the inexperience side of things," he said.
"We have been through some pretty big games over the last few years and like I said that's probably where some of the experience we think we have comes from.
"We've been in some pretty high pressure games and obviously this is going to be another step up but we are pretty comfortable on our abilities that we can go out there on Saturday night and play to the best of our abilities," he said.
Reece said centre Jack Goodhue was a smart defender and it made his job on the wing easier with him inside.
"He reads the pictures real well which allows you to be able to get up to your man to tackle him," he said.