Hansen has made six changes as New Zealand play for the first time since beating Australia 34-17 in the World Cup final.
Wales have not beaten the Kiwis in more than 62 years, a fact Hansen believes provides extra motivation.
"They are desperate to re-write some history so that makes them a really dangerous beast I think," Hansen said.
The Welsh run of 26 consecutive defeats against New Zealand includes three when Hansen was Wales coach between 2002 and 2004.
He added: "They see us as the team they want to beat and you know there's enough history been written about how long it's been - and it's going to happen one day.
"This is a really good Welsh side and it could happen this weekend if we don't turn up and play as well as we can."
Wales were outscored by five tries to one in a 27-13 defeat by England the last time they played, and coach Warren Gatland has made five changes from that match.
But Hansen believes the result was a reflection of Wales' lack of match-fitness rather than the quality of their performance.
He also thinks Wales are adapting their game to match the greater speed of matches in the southern hemisphere.
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"The northern hemisphere are starting to realise they have to change their game and we saw that against England," said Hansen.
"They hadn't played for some time ahead of that game and for the first 30-40 minutes against England they played really well.
"They fell away a little bit due to lack of game time in the second half so they have changed their game a little bit."
All Blacks coach Steve Hansen says Wales are a "dangerous beast" ahead of Saturday's first test in Auckland.