Fans and media inside the Azteca Stadium have been told to remain in their seats as severe weather descends on Mexico City ahead of the last-16 World Cup clash.
The match between Mexico and England is scheduled to kick off at 18:00 local time on Sunday, which is 01:00 BST on Monday morning.
Heavy rain has battered the city throughout the day, with reports of lightning visible above the famous stadium in the hours before kick-off.
Big screens inside the Azteca alerted supporters that an electrical storm was approaching and instructed them to stay in their seats, though many sought cover from the rain.
Under the rules in place, play cannot begin until 30 minutes have passed since lightning was last detected within an eight-mile radius of the stadium.
The mandatory 30-minute countdown clock resets each time a new lightning strike is detected within that distance, meaning delays could extend significantly.
When the countdown fully elapses, supporters can return to their seats and players will be given a short warm-up period before proceedings get underway.
Fifa has no power to create its own rules regarding severe weather delays and must adhere to the guidance issued by local authorities in the host country.
In the United States and Mexico, the recommendations of the National Oceanic and Atmospheric Administration are followed, requiring all play to stop if lightning is detected within eight miles of a venue.
When lightning risk increases, the safety of players and supporters takes priority, meaning all players must leave the pitch and fans must seek shelter away from their seats.
The arrivals of both teams at the stadium have been pushed back, though it remains unclear exactly when the sides will be permitted to enter the ground.
Fifa had earlier held talks with both the English and Mexican football associations on Friday after proposing the match be moved to 19:00 BST on Sunday, before a U-turn kept the original kick-off time in place.
Sources told BBC Sport that Fifa had been set to reschedule the fixture and confirm the change in a statement, but news of the proposal angered officials from both nations.
The English Football Association requested time to review the weather forecast in more detail before any decision was finalised.
Concerns over the impact on player preparation, fan travel, and the enormous logistical challenges of moving such a high-profile fixture were all discussed during those talks.
Fifa maintained no decision had been made and, following pushback from both associations, it was agreed the tie would remain at its scheduled time.
BBC meteorologist Tomasz Schafernaker warned that “any storms are likely to linger for hours,” adding that it remains “a close call” whether they stay away from the ground.
The match will be broadcast live on BBC TV, BBC iPlayer, BBC Radio 5 Live, and the BBC Sport website and app.
