Mexico resume World Cup qualifying on Friday when they welcome Costa Rica to the Estadio Azteca, and "welcome" may be the right word to describe teams coming to Mexico City now.
While the gigantic stadium in the Mexican capital used to be a fortress for Mexico, that is no longer the case, which severely weakens the national team's strength in CONCACAF.
For decades, nobody won at the Azteca. They didn't lose an official match at the stadium until 2001. The combination of over 100,000 fans (recent renovations have cut capacity to 87,000), thin air from altitude, heat and smog made the conditions brutal for opposing players.
Oh, and Mexico were also very good.
But then the final round of 2014 World Cup qualifying happened.
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Jamaica visited the Azteca to open the Hex in a match everyone figured would be an easy win for El Tri. But Mexico couldn't manage a single goal and the Reggae Boyz walked away with a shock 0-0 draw.
All of a sudden, the mystique of the Azteca had diminished, and it came at the worst time possible -- with the U.S. on their way to Mexico City.
Making matters worse, the U.S. had beaten Mexico at the Azteca in a friendly the year before. The Americans had confidence that they could get a result, something that wasn't the case for anyone going to the Azteca before.
Just like Jamaica, the U.S. held Mexico for 90 minutes and walked away with 0-0 draw.
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With a pair of draws and not a single home goal, nobody was sure what to make of Mexico at the Azteca. Costa Rica making it a third straight 0-0 draw didn't help. The fortress was no more.
It's bad enough to be unable to score at home. It's terrible to settle for a draw. But lose?
Mexico did that next, falling at the Azteca when Honduras visited. An early goal by Oribe Peralta made El Tri feel like they had figured things out, finally scoring in Mexico City, but two second half goals by the Catrachos handed Mexico just their second ever competitive loss at the Azteca.
Four home matches into the Hex and Mexico still hadn't won. They'd scored just one goal. And now they'd lost.
Finally, a win. El Tri were on the verge of missing the World Cup when Raul Jimenez came to their rescue. The striker's late, spectacular bicycle kick goal rescued a 2-1 win for Mexico and kept their chances of making the World Cup alive. It also delivered them their first (and only) win at the Azteca in the Hex, but even then, it took a late bicycle kick to do it.
The thinking was that 2018 World Cup qualifying would be different. The team appeared deeper and more talented, plus the calming influence of Juan Carlos Osorio had worked wonders. Next up was making the Azteca a fortress again.
Wins over El Salvador and Honduras in the semifinal round of qualifying helped, but then came Honduras, who came away with a 0-0 draw. That's a scoreline that's become all-too-common for Mexico in World Cup qualifying at the Azteca and, once again, the famous stadium in Mexico City looked pedestrian again.
That ugly 0-0 draw with Honduras was the last time Mexico played at the Azteca. In the meantime, El Tri went as far as considering moving qualifiers away from Mexico City, something unthinkable five years ago. But five years ago, one win from five Hex matches, including a loss, was unthinkable too.
Officials have speculated that with so many Mexicans now playing in Europe, the altitude now adversely affects El Tri as much as it does the visitors. To combat that, Osorio took Mexico to even higher altitude for training ahead of Friday's contest with Costa Rica, but will that be enough?
It used to be that Mexico winning at the Azteca was the most reliable thing in CONCACAF. That's no longer the case, but El Tri have to figure it out. They need their fortress back, whatever it takes.