As the Oakland Raiders prepare to take on the Houston Texans on Monday night at Azteca Stadium in Mexico City, some warn that the game could have adverse effects on the players participating.
Azteca Stadium is 7,280 feet above sea level, that's 2,000 feet higher than the NFL's most-elevated stadium -- the Broncos' Sports Authority Field at Mile High, which sits at 5,280 feet.
But it's not just the altitude that could leave players looking for oxygen masks. Former U.S. national soccer team star Eric Wynalda believes the air quality of Mexico's capital could also have harmful effects.
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"Azteca Stadium is the worst place to ever play a sporting event," Wynalda told USA Today.
"You can't breathe. The pollution is so bad that if you don't have some form of rain that's brought all that down you are going to be sucking wind.
"They (will) break a record for how many oxygen masks they have on the sidelines. The combination of being that high up with pollution is just devastating to the body."
If you don't want to take Wynalda's word for it, Jorge Avendano Reyes -- a local sports medicine and respiration doctor -- also thinks players might encounter troubling symptoms at Azteca, which is the only stadium that has hosted two soccer World Cup finals.
"There can be headaches, dizziness, sensation of fatigue, accelerated heartbeat, hyperventilation," Reyes told USA Today. "We can also have respiratory symptoms when we are exposed often to the pollution.
"The amount of oxygen that reaches the cells decreases, leading to the faster heartbeat and cardiac activity. The body tries to ventilate more quickly."
With players arriving Sunday, their bodies won't have time to adjust to the conditions. Wynalda is curious to see how the bigger athletes cope on the field.
"For American football, I really am curious to see how these guys handle it. It is going to have a massive effect on their body. These are some big bodies out there, 300 pounds people who are trying to get oxygen into their muscles and to their brains. I think you will see a lot of delay-of-game penalties."