Andy Farrell says Joe McCarthy's potential Test debut this week is a just reward for his work in recent months.
The 21-year-old has shot to prominence in the last year, making his Leinster debut in January off the back of his form for Dublin University in the All Ireland League, before touring New Zealand with Ireland during the summer.
And after he featured for an Ireland XV against the Maori All Blacks, as well as playing for Ireland A in their defeat to an All Black XV a fortnight ago, the second row will now win his first Test cap off the bench in Saturday's final Bank of Ireland Nations Series game against Australia.
McCarthy missed out on a potential first cap last week, having had to follow the return to play protocols for a head injury picked up while playing for Ireland A, and Farrell says he has full faith in the lock to make an impact off the bench this week.
"He's grown in many areas. He's obviously got a point of difference, and it's not just his size [6'7], it's his energy, it's his want to have big moments within the game," Farrell said.
"He's grown in all areas, and it's been great to take him on tour, and then Emerging Ireland. He didn't get much of an opportunity with the 'A' game, and he's been out of camp for a week, but he's earned the right to have a crack and show us what he's learned.
"It's not going to be perfect for him, but the bits we've been talking about over the last few months, we want to see improvement on that. He's a doer, Joe. He likes to get amongst it and get stuck in, so he won't shy away from the occasion, that's for sure. We're excited with what he'll bring off the bench."
With Joey Carbery suffering a head injury last week, Farrell has also handed an opportunity among the replacements to Munster's Jack Crowley.
And he has been hugely impressed with the 22-year-old outhalf, in what has been his first senior Irish camp this month.
"He has [Crowley] another week down the line as far as the experience of being in the group, and all the emotions going into a first cap is pretty daunting for anyone to handle, whether they admit it or not.
"He's got that off his back now, and is able to get down to how he'll get better as a player and help run the side, so he's been great this week.
"I like his composure, his character, and obviously he's a young kid. Like big Joe [McCarthy] who's making his debut, they're young kids, they'll make errors, but playing in a good side will help them develop."
With Bundee Aki back from suspension, Farrell has resisted the urge to put the Connacht man straight back into the centre, instead showing faith in Ulster's Stuart McCloskey, who has started the two previous games against South Africa and Fiji.
Jimmy O'Brien (below) also retains his place in the starting side, moving from full-back to right wing. It's the third different position the Kildare man will have played during the autumn window, having also replaced McCloskey in the centre during the win against the Springboks.
That versatility, along with his strong kicking game, has seen his international stock rise rapidly in recent months.
"Jimmy's got a left foot, which is pretty important in world rugby at this stage.
"There's always opportunity with injuries or form or what we're seeing in training, that always shapes you in different ways in every camp. But his form, him being in camps a couple of times before, and just seeing how unflappable he is, he has all the hallmarks of a great, composed international player.
"Somebody who can do what he does in many different positions, he doesn't flap around panicking about moving positions. He's just being himself wherever he's picked. Those things are pretty important in any international squad."
Wallabies coach Dave Rennie has made sweeping changes to his side from last week's defeat to Italy. With 10 changes in total, the Wallabies starting XV contains 12 of the side that ran France close in Paris a fortnight ago.
And the Irish coach says he's expecting the tourists to be back to their best on Saturday night.
"They have a couple of things to hang their hats on with regards to motivation but, in reality, 10 changes for them and they get the leaders back in the room, so there is a different vibe there from the start.
"Those guys are the ones that took the field against Scotland and came so close to winning in Paris. Like we have said all week, we know how difficult that is.
"I'm sure they will be using last week as motivation and putting that together with coming to the Aviva and taking our scalp and that will fire them up even more."
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