Head coach Andy Farrell expects Ireland to be “a hell of a lot slicker” in their Rugby World Cup opener following some disjointed warm-up displays.

The world’s top-ranked nation are among the pre-tournament favourites and launch their campaign on Saturday afternoon against Pool B minnows Romania in Bordeaux.

In-form Ireland arrived in France on a 13-match winning run but having failed to fully convince during last month’s disjointed victories over Italy, England and Samoa.

Farrell is untroubled by those patchy performances – produced by largely experimental line-ups – and has backed his players to deliver when it really matters.

“It’s certainly not a concern because obviously (they were) three warm-up games with different personnel and everyone is at different stages in the pre-season,” he said.

“It’s all galvanised to one point and this is it: the start of the competition.

“The performance should be one that’s a hell of a lot slicker, let’s put it that way.

“Understanding what it’s all about and getting down to business is where we’re at at this stage. We’re looking forward to getting going.”

Farrell has named a strong starting XV for the curtain raiser, albeit world player of the year Josh van der Flier begins on the bench, while wing Mack Hansen has the weekend off, despite being available.

Fly-half Johnny Sexton is back from a three-match ban to captain Ireland, while rookie lock Joe McCarthy is among the six starting World Cup debutants.

Farrell’s 33-man squad contains a total of 18 players who have never played on the biggest stage.

The Englishman feels there are benefits to that scenario but also suggested some of the newcomers need to avoid distractions better than they did around the recent Samoa game in Bayonne, when Ireland were based in nearby Biarritz.

“It’s an advantage because of the youthfulness and the quality of those players is top drawer,” he said.

“But they also need to understand what it is that they’re coming into.

“The reason we went there (to Biarritz) is that there’s a lot of distraction that goes on, certainly when you’re in a hotel that’s on the beach.

“Some people handled that brilliantly, some people didn’t. Learning from those experiences is pretty important because you don’t get second chances after this in World Cups.

“You have to wait four more years – if you’re lucky enough.”

Unfancied Romania are ranked 19th in the world. Farrell is braced for a physical assignment amid temperatures forecast to reach around 35 degrees Celsius.

“For anyone that’s watched them, it’s pretty clear and obvious that they’re a determined group,” said Farrell.

“I think by their own recollection they would say that their point of difference is their power, their aggression, their set-piece.

“They love mauling, they love the scrummaging part of the game. They’re very direct in the forwards and pretty nippy and dangerous within the backs as well.

“We’ve scouted them well but, at the same time, more of the concentration this week has been on ourselves.”