World ranking: Third
Qualification: 2015 quarter-finalists
Best result: Quarter-finals 1987, 91, 95, 2003, 11, 15
TAB odds: $7
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.
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