DANNAH O’BRIEN will become the 10th player to wear the Ireland 10 jersey since 2018 tomorrow.

It’s fair to say there has been no fully-established, regular, nailed-on out-half since Niamh Briggs last donned the green jersey four years ago.

The Ireland and Munster legend is now assistant coach to Greg McWilliams, who has gone with Tullow teenager O’Brien for Saturday’s first Test against Japan [11am Irish time, TG4].

McWilliams spoke highly of the 18-year-old recent Leaving Cert student yesterday, later hailing her as “phenomenal,” and adding, “I hope people get excited about watching her play. It’s not about heaping pressure on her. There’s no pressure on her. I just want her to go out and just be herself, and hopefully she can express herself the way she can.”

Enya Breen, who featured in the position during the Six Nations, is down to start at 12.

“For me, it shows the strengths of Enya Breen because the confidence I have in her is one of the reasons I have put her in there,” the head coach explained. “She has grown since the Six Nations, worked incredibly hard and her passing game has improved off both hands. Her game understanding is getting better.”

Nicole Cronin — “a baller,” McWilliams smiles, “I like her at 10 and nine” — is another option, though held in reserve tomorrow, while Molly Scuffil-McCabe is also versatile between scrum-half and full-back.

As we all well know, 10 is the big one. Playmaker, kicker, focal point.

Is it a case that McWilliams is happy to continue alternating and going with the flow, or would he prefer to nail down his out-half sooner rather than later?

“This is the perfect opportunity to be giving people an opportunity,” he responds. “Games like this very seldom happen so you have to experiment. What is our target? World Cup has to be a massive goal for us, getting on to the World Series.

“People will say, ‘Oh they’re testing another half-back combination.’ But there will be lots of them. We’re not in a rush here. This is a great chance for us to test players. I’m very comfortable with another combination the next week. People are working very hard and deserve a shot. Away we go and eventually the more people you have getting an opportunity, it’s a good thing. You need to be adaptive. In the women’s game you need to be able to play multiple positions. If we’re doing a good job coaching, players should be able to interchange. It shouldn’t be as rigid as, ‘Oh they’re trying another nine and 10′.

“And remember poor Kathryn Dane and Aoibheann Reilly are not here because of injury. So this is an amazing opportunity for Ailsa [Hughes, starting scrum-half] and Molly [Scuffil-McCabe] and Nicole [Cronin]. Ailsa came on against Scotland and was fantastic in that scoring zone when we needed it the most, she kept things going and stuck to task. Enya Breen scored that try but showed she had the bottle when needed and that’s a good quality.

“So she deserves this. So she could start next week or Molly could or Nicole, it will be somebody’s time. It’s not a bad thing, it’s positive that someone gives them opportunities. Whenever I leave this job, I hope people know I was prepared to give people a chance because everyone deserves a chance.”

O'Brien in action for Leinster U18s last year. Tommy Grealy / INPHO Tommy Grealy / INPHO / INPHO

From the outside looking in, that’s evident already. O’Brien is one of four uncapped players in the XV, alongside Natasja Behan, Aoife Dalton and Méabh Deely.

They make up a young, inexperienced backline, but there’s a huge sense of excitement around it too.

With that comes jeopardy, but it’s a risk McWilliams is willing to take.

“It was the same when we started Dan Leavy or Luke McGrath as 16-year-olds in school. You just have to see how they go. All of these girls are going to win multiple caps, it may not happen immediately but it will happen eventually.

“So they don’t need to how what they have straightaway. My goal as a head coach must be to demonstrate patience with these players. We don’t have an U20 side in Ireland so it’s not like we can throw them into that group So they will go back to AIL and interpros after this and it’s up to me to engage with the coaching staff in Ireland to make sure we’re developing them.

“Aoife Dalton is 18 and playing at 13 when she is normally a 12. Let’s see how she goes. If she struggles in the wider channels defensively, we will work on it to make sure she is better the next time. I’m prepared for big errors to happen and big learnings. And if we get the chance to work on our skills and the coaches to fix things, we’ll do that.

“It’s the only way we’ll get better. Throw them in and see what they’re like and if they don’t do it in the first Test, they’ll do it somewhere down the line. It’s exciting. We’re prepared for worst case scenarios as a group.”

And with a last word for the opposition, he concluded: “Japan play excellent rugby, their skillsets are really high and now that we’re on their home turf and we’re playing at their temperature, they’ll be big favourites but we’ve absolutely nothing to lose.

“We can give it everything we have and not worry.”