Steve Hansen believes Jaguares and Pumas have narrowed the gap on New Zealand sides

Steve Hansen has issued not just the Crusaders, but his own All Blacks, with a warning about the ominously strong state of Argentina rugby.

Veteran New Zealand Test coach Hansen said he can't help but be impressed by the giant strides made the Jaguares in the last year, noting this Saturday's Super Rugby final features the competition's two strongest teams.

While the Crusaders start favourites because of home advantage and their enviable pedigree, Hansen believes the South Americans provide a very real threat.

The Argentina Rugby Union (UAR) has succeeded in getting the Jaguares to work in closely with the Pumas program in a World Cup year, luring a number of additional Test candidates to the Super Rugby team.

No fewer than 37 of the 46-strong World Cup squad named by Argentina coach Mario Ledesma are aligned with this year's Jaguares.

A handful of big-name stars, such as five-eighth Nicolas Sanchez, are based in Europe but have previously represented the Jaguares, meaning they should slot easily into the national team's methods when they gather in Buenos Aires next week.

Hansen says it all points to a significant challenge to open the All Blacks' Test season at Velez Sarsfield on July 21, pointing at the flair on show when the Jaguares dissected the Brumbies 39-7 in last week's semi-final.

"They have always had big bruising forwards, but their backs have scored some sensational tries," Hansen told journalists.

"They really opened the Brumbies up and every opportunity they had off turnover ball they punished.

"They're playing with a lot of confidence and together as a team rather than as a group of individuals."

Traditionally renowned for their scrummaging, Hansen noted the Jaguares and Pumas have let that element of their game decline slightly in recent years to improve other aspects.

They played more of a "Super Rugby-type" game, employing the sort of ball movement that should be effective for the Pumas in the warm temperatures of Japan during the World Cup.

"The biggest weapon they've gained is confidence. They've got a belief," Hansen said.

"They're worthy finalists. They're going down there believing 100 per cent they can beat the Crusaders, so that will make them dangerous."