​England have already navigated a string of World Cup hurdles this summer, but Thomas Tuchel knows the real test that awaits in the cauldron of the Azteca Stadium for the last-16 clash. The co-hosts have been whipped into a feverish frenzy over the past three weeks, peaking with their dominant last-32 triumph over Ecuador. After a weather delay, Julian Quinonez and Raul Jimenez delivered decisive blows to leave their South American opponents reeling. Yet England’s biggest challenge on Sunday night may be the conditions, with altitude likely to be a great equaliser at Mexico City’s Azteca, perched 7,220 feet (2,240 metres) above sea level. The thinner air means less oxygen is available with every breath, turning many lung-busting recovery runs into even tougher tests. “There will be a lot of obstacles awaiting us,” England boss Tuchel said after their 2-1 win over DR Congo. “The altitude will be a big disadvantage because we cannot adapt to it in four days – it’s simply 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 we will have to deal with.”
To understand the science, the partial pressure of oxygen drops sharply at altitude, meaning oxygen molecules are more sparse in the air. Brendan Scott of Murdoch University explains that with fewer oxygen molecules in the same space, England’s players will breathe more heavily to try to increase oxygen uptake, but less oxygen reaching the muscles will inevitably dampen performance. Opponents who are less acclimatised to altitude often hold the upper hand, and Mexico’s record at the Azteca is formidable: 89 matches, 70 wins, 17 draws and only two defeats, plus a 10-game World Cup unbeaten run.
England have not played at the Azteca since the 1986 World Cup, when Diego Maradona’s memorable two goals featured prominently. Sir Bobby Robson took the squad to Mexico a year early to acclimatise, but Tuchel and the FA did not organise a similar plan in the build-up. The draw only became clear in December, leaving England to plan travel for Friday afternoon after their final session at the Kansas City training base, meaning arrival more than 48 hours before kick-off. With no 2-3 week acclimatisation window, the plan is to travel as late as possible, with a ceiling of 48 hours prior to kickoff, a strategy aimed at managing respiratory fatigue and preserving performance.