Severe thunderstorms in Mexico City caused a one-hour delay to the World Cup round-of-32 match.
The game is being held at the historic Estadio Azteca, with high tensions surrounding the encounter.
Diplomatic relations between the two nations remain strained following an embassy raid in Quito in 2024.
Mexico aims to reach the round of 16, hoping to replicate their successful 1970 and 1986 tournament runs.