World ranking: First
Qualification: 2015 quarter-finalists
Best result: Quarter-finals 1987, 91, 95, 2003, 11, 15
TAB odds: $8
Chances: Two wins over the All Blacks in as many years have established the Irish as bona fide contenders for the title. Those results show that, on their day, they can beat anyone.
How will they handle that expectation? As defending champions, they fell short in this year's Six Nations, losing to Wales and England, so their temperament is in question.
Probably the most complete prop in world rugby, Furlong was a star of the Lions tour of New Zealand two years ago. As good around the park as he is at set-piece, the 26-year-old anchors the best front row in Japan.
Like his younger propping partner, Healy is a devastating ball runner and powerful at scrum time. If Ireland are to make their deepest World Cup run, they need to dominate up front and Healy will be a big part of that gameplan.
Was the standout forward in Ireland's 16-9 upset of the All Blacks in November. He is an exceptional ball runner, who could adequately cover all three loose forward positions.
Stander is a complete rugby player - think Luke Jacobson on defence, Jerry Collins with ball in hand.
Outplayed Aaron Smith during the 2017 Lions tour, with three near-perfect halfback displays. The best box-kick in world rugby, he also possesses a bullet pass with a Justin Marshall-esque running game.
We all remember his match-winning try against the All Blacks in Dublin? One of the most exciting outside backs in world rugby, Stockdale has struggled with consistency at international level.
Expect Joe Schmidt to release the reins on his talented winger for the World Cup.
Forwards: Rory Best (captain), Tadhg Beirne, Jack Conan, Sean Cronin, Tadhg Furlong, Cian Healy, Dave Kilcoyne, Iain Henderson, Jean Kleyn, Peter O'Mahony, Andrew Porter, Rhys Ruddock, James Ryan, John Ryan, Niall Scannell, CJ Stander, Josh van der Flier.
Backs: Bundee Aki, Joey Carbery, Jack Carty, Andrew Conway, Keith Earls, Chris Farrell, Robbie Henshaw, Rob Kearney, Jordan Larmour, Luke McGrath, Conor Murray, Garry Ringrose, Jonathan Sexton, Jacob Stockdale.
Pool draw (NZT)
Ireland v Scotland, Yokohama City, 7:45pm (live updates)
Japan v Ireland, Shizuoka Prefecture, 7:15pm (live updates)
Ireland v Russia, Kobe City, 11:15pm
Ireland v Samoa, Fukuoka City, 11:45pm