As expected, Ireland coach Joe Schmidt has made wholesale changes to his starting team to play Romania at Wembley on Sunday, with Ian Madigan named at out-half.
Keith Earls, Jared Payne and Jamie Heaslip are the only survivors from the side that beat Canada 50-7 in Pool D last weekend.
Heaslip captains the side for the 4.45pm kick-off (live on RTÉ Radio 1).
Cian Healy and Tommy Bowe are both named in the side, while Paul O’Connell takes his place on a strong replacements bench.
Robbie Henshaw has failed to recover from hamstring trouble in time to make his World Cup debut.
Schmidt believes pitching Henshaw into action against Romania could have risked the Connacht centre's entire World Cup.
The Kiwi is confident the Connacht player will be ready to face Italy despite leaving the 21-year-old out of Sunday's Pool D clash at Wembley.
"It was just that at the start of the week we felt we had to take it a little bit easier than we first thought with Robbie," said Schmidt.
"He is fully running now and we just felt we'd rather not push ahead. Soft tissue injuries can be quite complicated.
"If you get a re-injury on the same site then you are in a situation where his World Cup could be in doubt. So we've taken no risk. There are times to take risks but this is a great opportunity for Darren Cave."
The Connacht centre is likely to be the only member of Ireland's squad left awaiting World Cup action after this weekend if boss Joe Schmidt empties his entire bench.
The Irish starting XV is the oldest in Rugby World Cup history with an average age of 29 years and 245 days.
"Well Eoin Reddan has probably contributed to that! Is it really?" joked a bemused Schmidt. "Hopefully the team won't show its age!"
Schmidt has named four World Cup debutants in his side to face Romania. Richardt Strauss, Devin Toner, Jordi Murphy and Cave will all make their tournament bows in London.
Versatile playmaker Madigan will start at 10, but Schmidt admitted the Leinster pivot could move to scrum-half during the course of the match.
Madigan is Ireland's third and emergency scrum-half, covering for Conor Murray and Reddan, with Schmidt keen to hand him a first Test run at nine this weekend.
"We want Ian (Madigan) and Paddy (Jackson) both to have some time at 10," said Schmidt. "But if the game's going in a direction where we feel Ian would benefit from 15 minutes at nine, then that's possible."
Ireland will be fully expected to ease past Romania in much the same vein as against Canada, hence the raft of changes from Schmidt.
The pivotal clashes in Pool D remain further ahead, with Italy and France the two main challengers for the top spot in the group and a likely quarter-final against Argentina.
Ireland: Simon Zebo, Tommy Bowe, Jared Payne, Darren Cave, Keith Earls, Ian Madigan, Eoin Reddan; Cian Healy, Richardt Strauss, Nathan White, Donnacha Ryan, Devin Toner, Jordi Murphy, Chris Henry, Jamie Heaslip.
Replacements: Sean Cronin, Jack McGrath, Tadhg Furlong, Paul O’Connell, Sean O’Brien, Conor Murray, Paddy Jackson, Rob Kearney.
Here's the @irishrugby team v @RugbyRomania #ShoulderToShoulder #RWC2015 pic.twitter.com/scVAJWwo3s
— Irish Rugby (@IrishRugby) September 25, 2015
