SCREENGRAB/BBC
England were booed as they arrived at their hotel to prepare for their World Cup last-16 game against Mexico - but that will be far from their main issue in Mexico City.
The Three Lions face the tournament co-hosts on Sunday (01:00 BST, Monday), a match which will be shown live on BBC One and iPlayer.
There is increased security at England's hotel after Ecuador, whom Mexico played in the last 32 in Mexico City, lodged a noise complaint with Fifa.
And Thomas Tuchel's side face further threats from the weather, the altitude and reportedly, even spying.
Before the last round Ecuador players were deliberately kept awake by local supporters, who used loudspeakers, horns and motorcycles outside the team hotel late at night.
Mexico went on to win 2-0.
Ecuador stayed in the Westin Hotel and England wanted to keep their whereabouts undisclosed, but there were concerns that the location would be leaked.
And hundreds of locals were waiting outside their hotel as the England team coach arrived on Friday, with some chanting "Mexico" and others booing.
Members of Mexico's National Guard lined the entrance to England's hotel, while police officers in riot gear stood next to barriers on the road outside the hotel.
England's players and staff will be offered natural sleep remedies or white noise machines to try to avoid sleep distruption from the potential overnight noise.
Some are likely to bring their own ear plugs or sleep bands too.
England attacking midfielder Morgan Rogers said: "I won't be happy if it wakes me up - I'll be honest.
"We'll see how it goes but we'll deal with it as best as possible. It's just another obstacle to overcome but we're ready."
As well as the noise, some people struggle to sleep in higher altitudes.
Will the game kick off on time?
England arrived two days before the game as Fifa rules for this stage of the tournament state that teams must hold a part-open training session in the local area the day before the match.
Their preparations were disrupted on Friday by a chaotic five-and-a-half-hour period in which it emerged that Fifa was considering bringing the match forward by six hours because of forecast storms.
The Football Association and Mexico's football federation (FMF) were angry at the proposal less than 48 hours before kick-off, and the game will now start as originally scheduled.
So while the game is now remaining at 18:00 local time, that remains subject to the weather - with delays possible.
Mexico's last match against Ecuador at the same venue was delayed by an hour because of thunder and lightning.
"Daily thunderstorms are normal in Mexico City at this time of year – but forecasts suggest the risk on Sunday is particularly high, and if those storms develop they could be severe," says BBC weather presenter Ben Rich.
"On Sunday these storms look likely to bring frequent lightning, and there is also the risk of hail.
"Thunderstorm activity tends to peak around, or just after, the highest temperatures of the day – during the late afternoon and into the evening, which could affect kick-off.
"Moving kick-off earlier could have allowed the match to take place before the worst of the thunderstorm activity gets going – although this is certainly not guaranteed."
A delay would not be good news for the players, the attending crowd... or the millions of fans in England who have stayed up into the early morning for the game.
Can England cope with the altitude?
England also face the challenge of playing the game at high altitude.
Mexico City has an average elevation of about 2,240m above sea level, meaning there is less oxygen available.
Ideally, athletes should spend a week or two living at that altitude to allow their bodies to acclimatise and generate more red blood cells.
England have only arrived in Mexico City two days before the match. Their first training session is at 16:00 local time (23:00 BST) at La Cantera.
Meanwhile, the co-hosts have played all their games so far at high altitude - with one in Guadalajara (1,500m above sea level) and three at the Azteca - so their players should be adjusted.
"Maximum aerobic capacity at this kind of altitude usually drops around 10%, and that has a knock-on to performance," says Dr. Barney Wainwright, senior research fellow at Leeds Beckett University.
"Maximum sprint speeds won't be affected, but players will need to wait a bit longer to recover from each one and go again."
Tuchel admits his team will be at a "big disadvantage because we cannot physically adapt to it".
In rugby union, England are facing South Africa on Saturday in Johannesburg, at an altitude of 1,753m - lower than the Azteca - and the team have been undertaking altitude preparations including training in the gym while wearing special masks which reduce the flow of oxygen into the body.
Could spying be a factor?
According to the Daily Mail, , externalone reason England delayed their trip from their base in Kansas City, Missouri to Mexico City was to avoid being spied upon.
The Three Lions trained on Friday at their camp in the USA - as they have done in between games all tournament.
However an extra day in Mexico City may have been beneficial on this occasion. But Tuchel reportedly wanted to make sure any tactics he tried out in training were kept secret.
The newspaper report says England's training ground in Kansas City was better protected by police and security guards from potential spying than La Cantera, which is Pumas' training ground in Mexico City.
