England have overcome several World Cup obstacles already this summer – yet Thomas Tuchel is fully aware of the seismic challenge that awaits at the cauldron that is the Azteca Stadium in the last-16.
The co-hosts have been whipped up into a piping-hot frenzy over the last three weeks, unleashed most impressively in their last-32 victory against Ecuador. Following a weather delay, the rampant Julian Quinonez and Raul Jimenez landed a pair of haymakers to leave their South American opponents dazed.
Yet England’s most daunting task on Sunday night could well be the conditions, with altitude set to be a great leveller with Mexico City’s iconic Azteca situated 7,220ft (2,240m) above sea level.
With the air thinner and less oxygen available to replenish the bloodstream with each sharp intake of breath, those lung-busting recovery runs become more excruciating at each turnover.
“There will be a lot of obstacles awaiting us,” said England boss Tuchel, after his side’s 2-1 win over DR Congo. “The altitude will be a big disadvantage, of course, because we cannot adapt to it in four days – it’s just impossible.
“We are ready for that. We have the ideal platform for that and we genuinely believe we are ready for that. When the going gets tough, we will be ready for that. It’s a huge advantage Mexico have. There’s not enough time. We knew that before.
“It’s just a disadvantage with which we will have to deal with.”
To get into the depths of the science, the partial pressure of oxygen in the air drops drastically at altitude, meaning that oxygen molecules are further apart due to less pressure pushing them together.
Murdoch University’s Brendan Scott details how, with fewer oxygen molecules in the same volume of air, England’s players will breathe more heavily to increase oxygen uptake. But with less oxygen reaching their muscles, their physical performance will unavoidably be impeded.
With opponents often less adapted to altitude, Mexico’s competitive record at the Azteca is formidable: 89 games played, 70 wins, 17 draws and only two defeats, not to mention 10 World Cup games unbeaten.
Back in 1986, Sir Bobby Robson took the squad to Mexico a year early to sample the conditions. No such plan was put in place by Tuchel or the FA in the build-up, though of course they only discovered their draw – and potential pathway to Sunday’s showdown – in December.
England plan on travelling on Friday afternoon, following a final session at their Kansas City training base, which means arriving more than 48 hours before kick-off.
The thought process is that, without the ideal 2-3 weeks of preparation to acclimatise to the conditions, the next-best move is to arrive as late as possible, with an upper limit of 48 hours before the serious issue of respiratory fatigue.
It is not a practice widely heralded, though. Well-known physical performance coach Steve Magness believes arriving two days before the game is “one of the worst arrival times for performance” as it’s “smack dab in the middle of the ‘dip’ of performance with limited acclimatisation.”
Clearly, it is not an exact science. Yet England can learn from their sporting counterparts if in need of a case study or two.
England’s men’s rugby team played in South Africa eight years ago, with then-coach Eddie Jones opting for a late arrival in Johannesburg, which is 1,753 meters (5,751 feet) above sea level, having prepared much closer to sea level in Durban.
Though common practice has seen opposition arrive within 24 hours of kick-off, that is not possible during a World Cup due to Fifa regulations.
The Three Lions may look to various performances across multiple sports in how to spread out their effort on Sunday, given the rugby XV led 24-3 after 20 minutes on that day in 2018 before wilting in a 42-39 defeat.
“It was tough after 20 minutes,” hooker Jamie George said, admitting that the altitude was a factor. “It really did kick in after 20 to 30 minutes; it definitely hit us quite hard.”
Endurance athletes are accustomed to training at altitude, with Callum Elson, a Great Britain runner and former Leeds United academy player, underlining the risk of players pushing themselves too far at the Azteca.
“I didn’t notice it living there, like walking around; it’s totally fine,” Elson tells The Independent, recalling various experiences at altitude camps, including Flagstaff, Arizona at 7,000 feet (2,130m).
“It’s only until you come across a steep hill or a set of stairs and it takes a bit more out of you than it usually would. It catches you off guard. The worst thing is not in the moment, sometimes it actually feels better, because the higher you are, the lower the air resistance.
“But it’s the recovery in between, so it’s that idea of trying to catch your breath, trying to let your heart rate get back down, once it’s up, it literally just doesn’t come down.”
As Elson notes, one way to illustrate the difficulty of combating altitude in elite sport is through time.
Roger Bannister broke four minutes in the mile 72 years ago, with that barrier now proving common, including 28 Brits in 2025 alone, yet that barrier is still extremely rare at altitude, including British runner Reece Sharman-Newell achieving it for the very first time in Colorado (5,337 feet) last year to underline an accepted conversion of 8-12 seconds depending on the exact elevation.
Naturally, in a team sport environment, with running merely part of the performance, England players could be further compromised.
While England’s task is monumental and they cannot afford to overlook Mexico, their chances of ultimately ending 60 years of hurt could take a dent due to the difficulty in recovering.
“As an athlete, my biggest concern would not be the 90 minutes… it’s actually if they get through,” Elson adds. England would play their quarter-final a week on Saturday against either Brazil or Norway in the heat of Miami.
“How absolutely exhausted are they going to be afterwards? Let’s say you use all your subs, let’s say they have to work as hard as they did against DR Congo, which is every man running his legs off.
“Even in the moment with the adrenaline and everything, they get through it. I think the after-effects of how they recover. That recovery, I think, will be the really hard bit.
“So, actually, there’s two things: there’s the focusing on how do we beat Mexico, but then there’s also, if we do beat Mexico, and we’ve gone through everyone in the squad pretty much in the Mexico game, how do we recover to possibly to go again?
“It’s one of those where I think a lot of people would say: should we have picked a squad that is less industrious and more skilful on the ball, in terms of can we in the Mexico game, if we’re 25 minutes in and everyone’s gone, go ‘alright, bloody hell, this is intense now.’
“Because not only do we have all the fans against us, not only is it humid, not only are we at altitude, could we just put our foot on the ball for five minutes and keep it?”
Finally, however, a point of solace for the England squad: it should be noted that plenty of the Mexican squad, such as Jimenez in London with Fulham or Quinonez in Saudi Arabia, do not actually live at altitude.
The difference, however, is that Mexico have played all but one of their four games at the Azteca. They also held a pre-tournament camp in their own country. On Sunday, in the heat of battle, we’ll see how influential the contrasts in preparation really is.
