Mexico were on top throughout at a wet Estadio das Nunas in Natal, and Oribe Peralta's goal in the 61st minute was enough for them to get off to a winning start in Group A at the expense of Cameroon.
In a first half that had few clear-cut chances for either side, it was the officials who stole the headlines for the wrong reasons, less than 24 hours after Brazil were awarded a controversial penalty in their 3-1 win against Croatia.
Former Tottenham Hotspur attacking midfielder Giovanni dos Santos thought that he scored two goals, one on 10 minutes and the other just past the half-hour mark, but both were ruled out by the linesman for offside. However, replays showed that both goals should have stood.
After half time, Peralta missed a great opportunity on 47 minutes when his shot from close range was blocked by former Liverpool goalkeeper Charles Itandje.
However, the 61st minute of the match was when the first chance was taken by Mexico. A Dos Santos shot was saved well by Itandje, only for Club America striker Peralta to pounce on the rebound and score his ninth goal for Mexico in seven appearances.