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It's not just the altitude, though the 2300 metre elevation of the stadium makes it harder to breathe - and even think - as lungs gasp and muscles ache, especially if you are constantly chasing the ball.
The All Whites are playing in the early afternoon (2.30pm local time), when the air pollution is at its worst. It will be hot, with a cacophony of noise that few stadiums can match.
"It's a unique experience - and not often in a good way," says former All White Simon Elliott, one of the few New Zealanders to have experienced the Azteca.
"The altitude, combined with the smog, is extremely tough. You feel like you are swimming a little bit or going through quicksand. That is why keeping the ball is so important; you don't want to be doing a lot of work without the ball."
During his stint at LA Galaxy (1999-2003), Elliott played several times in Mexico City in regional competitions
"It's the whole package," says Elliott. "The heat, the noise, the smog, the crowd..it's a great place to play but you can suffer."
On Thursday morning the All Whites will prepare in changing rooms that date from the 1960s. Across the corridor they will hear the Mexicans, psyching themselves up with shouts of "Vamos! Vamos! Vamos! (Let's go, Come on!)" then walk down a tunnel before emerging into the arena.
"It's a cauldron," says Elliott. "You come out from underneath and you are hit by a sea of fans ... the smell, the sweat and the noise. At least New Zealand is a bit of an unknown quantity. If it was the USA playing Mexico there would be potential for a riot."
Former American players have described seeing effigies of players burning before kick off in the grandstands. They talk about basketball size balls of straw being set alight and thrown from the stands, as well as bags filled with urine, batteries, coins and other projectiles.
There is no real danger - the field is a large distance from the stands and such incidents may belong more to another time (the 1980s), or be more typical of the intense cross border rivalry. But with what is at stake, intimidation - both on the field and from the stands - won't be in short supply.
"If you have not played at Azteca, there is nothing you can be told that can prepare you for it," former American international Cobi Jones (168 matches) told ESPN.
"There is no way to counter the altitude, no matter how fit you are. You need to keep it simple and smart. The Mexicans will press you. They love to attack players who have not been there, especially at the back. They also know there is simply nothing like [the Azteca]."
Communication will be near impossible at times, especially for defenders - it is difficult to hear anything from a team-mate more than 20 metres away. Teams there rely on established defensive combinations, which the All Whites sans Ryan Nelsen and Winston Reid don't really have.
"It will be deafening," says All Whites goal keeper Glen Moss. "We need to make sure everything is nailed down, everyone knows their jobs and what to do in different scenarios so we don't have to rely on that communication aspect."
- by Michael Burgess in Los Angeles