Cobargo’s Millie Boyle featured in her first World Cup outing where a missed conversion proved costly for the Australian contingent.
Kicking proved key to the result, with the hosts holding out for a 19-17 win in the early hours of Thursday morning.
Both sides crossed for three tries each, with conversions proving to be the difference with the Irish flyhalf Nora Stapleton slotting two-from-three attempts.
The Australian Sevens contingent had a strong influence on the match with Captain Shannon Parry and Mahalia Murphy both crossing the try line.
The narrow loss of just two points means that Australia has earned a losing bonus point, placing them in their position in Pool C on one point, trailing Ireland (four points) and France (five points).
“It was a very physical game and a devastating loss by two points,” Boyle said after the game, recovering from a couple of head-knocks.
Boyle earned praise for her debut World Cup performance, pairing up well with fellow lock Chloe Butler alongside captain Shannon Parry and Grace Hamilton for a number of devastating runs up the middle, but also showed incredible line speed in defence.
Wallaroos head coach Paul Verrell said: “I’m proud of the way the team performed tonight, they put in a big effort and overall it was a great improvement from our tour of New Zealand.”
“The team matched it with the Irish and for the majority of the match and matched them in physically and put in a solid defensive display.
“The Irish controlled possession for a large portion of the second half and kept the ball inside our own half and that prevented us from creating any real opportunities.”
The Wallaroos found it hard going in the second half as the Irish squad worked hard to defend a 19-10 lead.
However, officials said the forwards were responsible for a series of scything runs that had the tourists in reach of an upset.
In the 73rd minute, Hilisha Samoa dived over to keep the Wallaroos in the hunt.
Ash Hewson slotted the conversion to narrow the score to 19-17, becoming the Wallaroos all-time leading point scorer in the process.
With just a few minutes to play, the host nation slowed down play, eventually kicking the ball dead to retain the lead.
Despite the loss, Verrell said the match was indicative of the hard work the Wallaroos had been doing in preparation.
“We could see the content we’ve been going over in training being put into practise, but we need to continue to build as we turn our focus to France.”
Australia will now prepare for its second match of the tournament against France on Monday 14 August at 4.45am AEST.