Hansen says favourites Ireland must avoid being World Cup 'chokers'
Hansen was head coach when New Zealand won the World Cup in 2015.
He was also assistant to Sir Graham Henry when the All Blacks claimed the 2011 title.
Ireland underlined their status as the world's number one ranked team after beating England 29-16 in Dublin on Saturday and being crowned Six Nations champions.
Hansen says Ireland, under English coach Andy Farrell, must handle the pressure of being tagged among the World Cup "favourites".
"They're going well, ranked number one in the world, and they've had a great year so far," said Hansen, who will coach the Barbarians against a World XV at Twickenham in May.
"Every time a team is number one in the world, you've got to consider them to be a World Cup contender – but it's a tough tournament to win."
Ireland have been drawn in the same World Cup pool as reigning champions South Africa, Scotland, Tonga and Romania.
Hansen noted that Ireland has never got past the quarter-finals of a Rugby World Cup.
"So, they've seemed to struggle a little bit at World Cups. If it was the All Blacks, they'd probably be called 'chokers'," the New Zealander added.
"They've come a long way, they believe in themselves. They're a very good side, so they're definitely a contender.
"But they'll have to overcome the pressure of not having gone past the quarter-finals before.
"If they get through to the semi-finals, then they're in new territory.
"That’s something they'll have to deal with that they've never dealt with before."
Ireland secured a first-ever Test series win on New Zealand soil last year by securing back-to-back victories over the All Blacks.
New Zealand's form was erratic in 2022, but Hansen warned against dismissing the All Blacks as Rugby World Cup contenders.
"Beware an All Black team that's not considered 'good enough' to be winners of the World Cup – because that can come back and bite you."