Ireland will be expected to run out comfortable winners at Wembley against Romania in their second Pool D game.
With tougher tests against Italy and France in the coming weeks, coach Joe Schmidt has rested several key men, including fly-half Johnny Sexton.
Ireland are fielding the oldest starting XV in World Cup history.
Romania flanker Valentin Ursache must sit out the game after being suspended for one match for a dangerous tackle.
Ursache was cited by independent citing commissioner James Absaloms of Kenya after the 38-11 loss to France on Wednesday at the Olympic Stadium.
Schmidt has made 12 changes from the side that defeated Canada 50-7 and he hopes to gain further momentum against the world's 17th ranked side.
"There's a realisation from the players that it's an opportunity, but also a massive responsibility, to ensure that we get the result, and that's going to take a bit of work," said Schmidt.
The Ireland coach will be particularly keen to assess the continued return to peak fitness of Cian Healy, who will start at prop in the Pool D clash.
Ireland's remaining World Cup Pool D games
Sunday, 4 Oct, 16:45 BST: Ireland v Italy, Olympic Stadium
Sunday, 11 Oct, 16:45 BST: Ireland v France, Millennium Stadium
The British and Irish Lion missed all of Ireland's warm-up games with a neck injury and returned to action for the first time since April as a replacement against Canada.
"Cian is always an asset, whether he's in the starting team or off the bench," Schmidt said.
"I think he came off the bench mostly through the Six Nations, but the one start he did get, against Scotland, he got two turnovers in the first 20 minutes on the ground."
The teams last met 10 years ago at Lansdowne Road, with Ireland emerging 43-12 victors.
Romania full-back Catalin Fercu started that game and Ireland scrum-half Conor Murray said he was one to keep an eye on.
"He's well capable of countering, with their wingers as well. Both their nines are quite dangerous as well. If they get into broken play they really back themselves, especially after a line break or something like that," Murray said.
Fercu is still one try from becoming Romania's record try-scorer, having been stuck on 28 for 17 Tests stretching back more than two years.
Teams
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 (capt).
Replacements: Sean Cronin, Jack McGrath, Tadhg Furlong, Paul O'Connell, Sean O'Brien, Conor Murray, Paddy Jackson, Rob Kearney.
Romania: Catalin Fercu; Adrian Apostol, Paula Kinikinilau, Csaba Gal, Ionut Botezatu; Michael Wiringi, Valentin Calafeteanu; Andrei Ursache, Andrei Radoi, Paulica Ion; Valentin Poparlan, Ovidiu Tonita; Valentin Ursache, Mihai Macovei (capt), Daniel Carpo
Replacements: Mihaita Lazar, Otar Turashvili, Alexandru Tarus, Johannes van Heerden, Stelian Burcea, Florin Surugiu, Florin Ionita, Florin Vlaicu.
