Wales have not been above Argentina in the world rankings since October 1, 2023, and that was only for a fortnight before that quarter-final defeat.
Tandy takes over a side ranked 12th, a position that the Pumas have not been as low as since October 2014.
Argentina have been a constant in the top 10 since then and will hope to keep pushing by enjoying strong autumn results.
Getting off to a strong start is crucial ahead of what appear to be tougher Tests at Murrayfield and Twickenham.
The new-look Wales set-up has presented analytical challenges this week as the Pumas prepared at St Peter’s RFC in Cardiff.
“We don’t know what to expect from Wales in terms of the tactics or strategy, but they will be tough to beat because they always fight and have quality,” said captain Montoya.
“They have a very good coaching ticket with Steve Tandy, Danny Wilson, Matt Sherratt plus Dan Lydiate and Duncan Jones,” said Contepomi.
“They are very good coaches, so I expect them to be a very knowledgeable team.
“We admire Wales’ passion and how they never give up. They live and breathe rugby so we are expecting a highly-motivated team in one of the best stadiums in the world.
“We are expecting a very, very tough encounter because Wales are highly motivated to start a new era well and they are a team with quality throughout their 23.”
Argentina might be keen to talk up their hosts, but must also cope with great expectations.