Johnny Sexton is certain to travel to face the All Blacks in July and it is up to Joey Carbery to convince Andy Farrell that he deserves to start in at least one of the Test games.
That's the view of Ronan O'Gara, who concedes that he can't make a solid judgement on Carbery's standing with Farrell because he doesn't know what goes on day by day in camp Ireland.
What the Munster and Ireland great is certain about is that Ireland will be facing a "fresh" New Zealand team coming off their Super Rugby season that will be "hungry" to regain reputational ground after November's northern hemisphere losses to Ireland and France.
Playing the All Blacks on their own turf, for Ireland or the Lions, was always a tough proposition in the New Zealand winter for Ronan O'Gara.
But his perspective of that country changed when he spent two years there coaching with the Crusaders.
"New Zealand look forward to new prey coming into their territory," warned the 45-year-old.
“But saying that, there were numerous occasions where we could have got the job done but we didn't."
O'Gara, who played there on six tours, believes Andy Farrell's squad should be the best prepared for the challenge of any Ireland team that has gone there.
"It was dark until 10am and it got dark again at 4pm. It rained and it rained hard," he recalled.
"It will be wet rugby on good pitches, presumably. It will be cold. But what has happened in my time playing, it was the end of a long season.
"Player welfare was good in our day, I'm not making any excuses in that regard. But now, you nearly have Club Ireland going on with the importance of the World Cup.
“It's happening in the French game as well, it's Club France.
"They're spending so much time together that what it takes importance in the mindset of a Gregory Alldritt, or Uni Atonio or a Tadhg Furlong or a Bundee Aki, it's the Test calendar.
“This is what the best players want to do. They want to prioritise, and rightly, playing for their country and then playing Champions Cup and then afterwards, it's uncompromising because there is the Top 14, which is taken very seriously.
“In Ireland, it's the URC, which top players play very little in and there's a reason for that."
It has been suggested that Farrell should consider resting Sexton, who will turn 37 during the tour.
But O'Gara believes this is an important trip in the development of this Ireland team and that he will lead the squad there.
"He’s the captain, I can’t see how he won’t go," said the Corkman.
"Yes, it’s Johnny Sexton but I don’t see how it’s a difficult conversation for Andy Farrell either way because he’s the boss.
"He does how he sees what’s best for Irish rugby and for Johnny Sexton and for the team, knowing that Johnny is an integral part of the set-up.
"When it comes to a competition like a World Cup or a Six Nations, especially a World Cup, it’s Saturday, Saturday, Saturday, Saturday, Saturday - that, at that age, is difficult to do.
"If he plays 50 minutes every week, for me, that would be huge. You need to have someone to start for 50 minutes, Johnny to play the last 30, or Johnny to play the starting 50.
"It’s very hard on the human body, we know it breaks down when you keep pushing it. That’s not an opinion, these are probably a few medical facts.
"What’s important by the time you come home from New Zealand is you have a clearer picture of the out-half scenario, the tighthead scenario, the loosehead scenario, the five backrows you want for three positions scenario.
"The back three and midfield is hugely competitive."
O'Gara adds that Farrell must consider bringing up to four out-halves on this trip.
"It’s a time for people to make their mark," he stated.
"I’d use it as an opportunity to show to your fellow players and staff what your character is, how you’d like to be seen by your fellow players.
"This is the place to do it. New Zealand.
"It is one of the hardest venues in world rugby to achieve something."
When Sexton was injured against France, Carbery started his first Six Nations game and did well - but was then only used as a 79th minute sub at Twickenham.
He got six more minutes against Scotland last Saturday, but came on at full-back.
O'Gara said: "Joey was available for the England and Scotland games and wasn't used so that would be, I would say, a deep frustration of his.
"But the other side of it is, Johnny Sexton is the captain and he's playing well, so you have to budge him out of the team. They're not just going to hand it to you.
"For Joey to start two (Tests), I've no idea is he good in training, how does he bring the players around him into the game, is that a strength of his or a weakness? Just because it's him coming in do the players knock off a bit subconsciously, because it's not Johnny barking at them?
"There's so many hidden variables in the make-up of creating a high performing team that we, on the outside, aren't privy to.
"But what is certain is that you get better, no matter how difficult the experience is, by getting minutes in that position."
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