The next challenge for them is beating a Russian team that although going down 53-17 to Italy, at least drew some encouragement from scoring their first three World Cup tries.
A calf strain has thrown Tommy Bowe's participation in Sunday's game into some doubt, although the Irish management may have taken the decision to rest him anyway.
Asked about the significance of the win over the Wallabies, Bowe said: "It's given us a huge amount of confidence, but I think within the team there just seemed to be something building for the whole week.
"A couple of weeks ago one of the players was on the phone to a mate of his over here (in New Zealand) and he was telling him how we will beat the Aussies, and your man was on the other end of the phone didn't quite believe it.
"There has been that positivity and that feeling the whole way leading up to that game, and it was nice to go out and do it.
"We can give anyone (in the World Cup) as good a go as we can. We lifted our intensity hugely for the weekend but it's huge for us now not to let ourselves down.
"We have to respect ourselves as a team and not peak with a huge match like that and then drop it for a match like Russia or Italy. That's the baseline, the platform set, and the pressure will be on us to try and keep to that now."
Bowe's try double against the USA has taken him to within one score of 100 Test points for Ireland. He is keen to put together a run of appearances now after a foot injury left him with just one 80-minute runout before the tournament.
"I'm feeling good. I still feel that I want to get more game-time, having missed out on quite a lot of pre-season and the warm-up matches," added the winger.
"I just picked up a little bit of a calf strain. I haven't done much in the last couple of days on it, but hopefully I'll be good to go for the weekend."
Meanwhile, Rob Kearney, who won his 30th Irish cap against Australia, wants the men in green to lay down an early marker against the Russians and immediately stamp out their hopes of causing a major upset.
"You probably would expect it, on paper, to be our easiest pool match, yes, but I think the World Cup has shown over the last number of weeks, these lesser teams are getting better and there's going to be more and more upsets," warned the full-back.
"If you don't come out of the blocks in the first 20 minutes and make a strong start and you give these other opponents hope, they get into the game more and things start flowing for them.
"So, probably of all the pool games, we would consider this maybe to be the least difficult but that's only on paper. Sport's very different and once the whistle blows anything can happen. So we need to be fully on our game."
Ireland and Russia have only met once before on the international stage. It was a Rugby World Cup qualifier in Krasnoyarsk nine years ago which the Irish won 35-3. Brian O'Driscoll, Ronan O'Gara and Leo Cullen are the only survivors from the squad currently in New Zealand.
Like Bowe, Kearney is hungry for more minutes on the pitch, especially as he has played just three times since sustaining a season-ending knee injury against New Zealand last November.
The 25-year-old, who has recovered from a groin strain most recently, admitted: "I want to play as much as possible. I haven't played a huge amount over the last year and I don't feel quite there just yet.
"That's going to come with more games and more time on the field. The more minutes I can get the happier and more comfortable I'll feel out there."
Follow the Ireland team in New Zealand on www.twitter.com/irfurugby.