- Steve Hansen's team suffered a major bump on their run-in to the World Cup.
- Ireland's 16-9 victory over the All Blacks in Dublin in November was built on a teak-tough defence.
- New Zealand top the world rankings, followed by Ireland, Wales and England.
Double defending champions New Zealand will head into the 2019 World Cup in Japan as favourites, but Six Nations Grand Slam champions Ireland have proven there are chinks in the All Black armour.
Steve Hansen's team suffered a major bump on their run-in to the World Cup when they went down to a second defeat in three games by a Johnny Sexton-inspired Ireland, whose provincial side Leinster won the European Champions Cup, Munster also making the last four.
That followed the Springboks' 36-34 victory in Wellington in September that ended a 15-match winning streak for the All Blacks, who have dominated world rugby since securing their second World Cup title in England in 2015 after previous success on home turf in 2011.
Excluding the 24-21 defeat by the British and Irish Lions in the drawn series in 2017, it was New Zealand's first defeat at home since 2009.
Ireland's 16-9 victory over the All Blacks in Dublin in November was built on a teak-tough defence organised by former England assistant coach and dual code international Andy Farrell -- the father of England fly-half Owen -- who will take over the reins from current coach Joe Schmidt post-World Cup.
"As of now they are the number-one team in the world," Hansen said. "So if you want to make them World Cup favourites, go ahead. I guess they are favourites."
The bookies say not, however, with New Zealand installed above Ireland, England, South Africa and Wales.
New Zealand top the world rankings, followed by Ireland, Wales and England and it is hard to envisage a World Cup like the last one when the southern hemisphere provided all four semi-finalists.
England, who had a catastrophic 2015 World Cup on home soil as they failed to advance from their pool, finished 2018 with an impressive mix of forward power and stylish back-line play during a 37-18 win over Australia, the losing finalists three years ago, at Twickenham.
It meant they had won three of their four November Tests, the lone loss an agonising 16-15 defeat by New Zealand.