That’s according to Joe Schmidt, who admitted that both he and the Ireland squad were “gutted” to see O’Brien suffer a fresh setback that has ruled him out for at least the next couple of months.
The Tullow native is set to undergo surgery and Schmidt revealed O’Brien had already turned his focus to the rehab required to miss as little time as possible.
The 31-year old missed the majority of last season with a shoulder problem and the latest setback will come as a major blow to Schmidt’s plans for the rest of the month.
“Sean has broken his right arm so he obviously won’t be available fo the rest of the Guinness Series,” Schmidt confirmed.
“He’s gutted. I am gutted for him. I think the team are. I actually thought he was just getting into the rhythm of the game.
“Talking to him after the game, he is already thinking about his rehab and trying to make sure that he gets back.
“He’s got a big target in a year’s time (World Cup) that he wants to get to. I think I described him as a stubborn man on Thursday. I think that ability to bounce back, that resilience that he has, will still give him a chance of getting back in time, towards the end of the year and then into the Six Nations.”
Schmidt insisted that it is “highly unlikely” that Conor Murray will into the equation for the visit of the All Blacks to Dublin next weekend.
The Munster scrum-half hasn’t played yet this season as he battles against a troublesome neck injury, with Schmidt admitting that he will not put on any pressure on Murray to make a comeback ahead of schedule.
“It’s not the injury, it’s really just how ready Conor is and how fully fit he is,” Schmidt continued.
“The injury itself has gone really well. It is tough to throw him back into a game of that magnitude. It’s highly unlikely that he will be involved but I will talk to him tomorrow.”
Robbie Henshaw will be assessed over the coming days after he pulled up in the warm-up with a tight hamstring.
“We are hopeful because we didn’t push him,” Schmidt maintained.
“We could have tried to see how he went on the pitch but it was right towards the end of warm up and we just felt that it would a two-fold risk: one, would he do more damage? And two, it’s always difficult if you’ve got to substitute someone five minutes into a Test match, when you have a limited number of substitutes.”
Kieran Marmion also hobbled off before the hour mark with a leg injury, with his replacement Luke McGrath enjoying a fine cameo including the try that killed off Argentina’s challenge.
“He rolled his ankle and if you watch on, he does play on so we would be very hopeful that he will be fine,” the Ireland head coach admitted.
“He might have to elevate his ankle for the next 24 or 48 hours and get a bit of ice on it but we would be relatively confident that he will be okay.”
Garry Ringrose (hip) and Rob Kearney (shoulder) are also expected to be fit enough to face New Zealand.
“They are going really well. Our prediction is that they will train fully on Monday so with that prediction, that puts them into the mix for sure. In the context of some of the guys who are doubtful, that is really important to us.”
The attention now turns to the world champions as Schmidt looks to get one over on his home country in Dublin for the first time.
“It has so little to to do with me,” he added.
“I would be delighted if we could be as competitive as we were the last three times we played them.
“There was the one in 2013, I am still bleeding from that. It hurts when that happens, and while Chicago was a great band aid, in fact it was a full bandage, it was great, but two weeks later we were very much in the game and it was very, very tough.
“The challenge for our guys is to step up and I’m confident they can. At the same time I am well aware of the challenge that the All Blacks present.”