Ireland assistant coach Mike Catt says wing Mack Hansen's absence from Saturday's World Cup opener against Romania is a selection call and nothing to do with discipline.

Hansen started in all of Ireland's Grand Slam campaign this year but Keith Earls has got the nod in Bordeaux.

"There is nothing that Mack has done wrong," said Catt.

"It's not that he's performed badly at all. He's done exceptionally well in his pre-season games."

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Coach Andy Farrell confirmed the 25-year-old Hansen was not injured when announcing his team for the Romania game on Thursday.

The Englishman then volunteered information about some members of his squad not dealing well with off-field distractions when they were based in Biarritz for their final warm-up game against Samoa in nearby Bayonne.

"The reason we went there is that there's a lot of distraction that goes on, certainly when you're in a hotel that's on the beach," Farrell added in response to a question about newer members of his squad not having World Cup baggage.

"Some people handled that brilliantly, some people didn't."

When asked directly on Friday whether Hansen's surprise omission was because of a disciplinary issue, Catt replied: "Not at all. Definitely not.

"It's a long competition and we need to keep people fresh too."

Centre Bundee Aki, who was sitting next to Catt at Friday's news conference, joked that Hansen's absence was performance-related as he added: "He was useless."

'It's definitely not about easing ourselves in'

The world's top-ranked team won all last month's warm-up games against Italy, England and Samoa to extend their victory sequence to 13 Tests.

But the performances were patchy and Catt said the Ireland coaches have been emphasising the need for increased "accuracy".

"From a coaching point of view we've really driven the accuracy part going into this game and the next four, five weeks because it's crucial that we get that right," added the former England star.

"The boys have trained exceptionally well but, as has been alluded to, we've haven't been accurate enough in our pre-season games."

Lock James Ryan also insisted the Irish must show "real intent" on Saturday even though they will be facing a Romanian team not expected to challenge them.

"It's definitely not about easing ourselves in," added the second row.

"If you are going to take this competition seriously, I don't think you can ease your way into any game. You've got to go in with the right mentality.

"We were a bit off in a couple of the pre-season games. We didn't hit that 80-minute performance we were looking for so tomorrow for us is about winning every moment or as many moments as we can."