Donnacha Ryan and Andrew Trimble return for Ireland

Joe Schmidt will reduce his 46-man Ireland training panel to "38 or 39" players before Scotland come to Dublin next week.

“There are some really tough decisions to make for the coaching group,” said Schmidt. “We have had a number of discussions of when to narrow the group. Over the next week or so that inevitably has to happen. Those decisions alone are tough enough, we might end up with 38 or 39 in a week’s time then we will keep working our way from there.”

So while Saturday’s trip to Cardiff may be the first game of the season, it’s already last chance saloon for several players. From Tommy O’Donnell in the backrow to Felix Jones at fullback, it’s the only opportunity for five or six established internationals to play themselves into the 31 man World Cup squad that must be submitted by August 31st.

“I wouldn’t say it’s their one opportunity,” Schmidt countered. “We are taking note of how they have trained. It is a very narrow window - 40 minutes each way - to make or break but it is the litmus test. It is where we find out, in a big stadium, in front of a big crowd, whether they can stay in the game, physically, mentally deliver what will be required.

“It’s probably the best examination but it has been an examination over the past six weeks.”

It’s the first time Keith Earls and Donnacha Ryan - following long term injuries - have been selected by Schmidt.

“I’m very appreciative of where I am, to be able to get the opportunity to even go out and run again this morning,” said Ryan, who was a bolter for the 2011 squad as blindside cover but has struggled with a foot problem for two years.

After a strong finish for Munster last season, Earls gets a run at outside centre.

Schmidt also confirmed the Scottish (August 15th) and Welsh (August 29th) visits to Dublin will primarily be used to get his frontliners match fit. That makes it almost concerning to be named in this 23-man squad. There is no place for Gordon D’Arcy as Darren Cave joins Earls in midfield with Paddy Jackson now, seemingly, Jonathan Sexton’s under-study. Ian Madigan is on the bench, where he has and probably will remain during the Pool matches against Italy and France.

Eoin Reddan starts with Kieran Marmion currently sneaking ahead of Isaac Boss as the third scrumhalf.

Presuming that six halfbacks will travel, only eight more backs will make the final cut. Rob Kearney, Tommy Bowe, Jared Payne, Robbie Henshaw and, if fit, Luke Fitzgerald are certainties. That leaves three slots between Noel Reid, D’Arcy, Cave, Andrew Trimble, Fergus McFadden, Craig Gilroy, Earls, Felix Jones, Dave Kearney and Simon Zebo, who wears 23 at the Millennium stadium.

Chris Henry, Jordi Murphy and O’Donnell appear to be in competition for two backrow spots with Iain Henderson’s versatility and Ryan’s experience making them ideal cover for Devin Toner and Paul O’Connell.

Ulster’s Dan Tuohy is the other option.

Cian Healy’s struggle to recover from neck surgery opens the door for Munster loosehead Dave Kilcoyne but Jack McGrath starts. Michael Bent’s ability to play both sides of the scrum makes the decision to parachute the Kiwi into the Ireland team that played South Africa in 2012 - before he even trained with Leinster - seem almost wise now.

Marty Moore, Sean Cronin, Healy and Fitzgerald are the only players not considered due to injury.

“What we did stack up at the start is that some players will not get an opportunity,” Schmidt added.

That makes this a massive game (kick-off 2.30pm, live BBC Wales).

IRELAND: Felix Jones; Andrew Trimble, Keith Earls, Darren Cave, Fergus McFadden; Paddy Jackson, Eoin Reddan; Jack McGrath, Richardt Strauss, Mike Ross; Iain Henderson, Donnacha Ryan; Jordi Murphy, Tommy O'Donnell, Jamie Heaslip (capt).

Replacements: Rory Best, Dave Kilcoyne, Michael Bent, Dan Tuohy, Chris Henry, Kieran Marmion, Ian Madigan, Simon Zebo.