Giovanni Dos Santos twice had goals disallowed as Mexico and Cameroon played through a scoreless first half in torrential rain in their opening match in Group A.

Dos Santos appeared to have put Mexico ahead in the 11th minute, but was ruled offside. He headed in from a corner in the 29th but it was called back when referee Wilmer Roldan appeared to call a foul in front of Cameroon goalkeeper Charles Intandje.

The heat was supposed to be a factor in this balmy coastal city, but heavy rain swamped the Arenas das Dunas for four hours Friday morning and continued through the first half, creating a slick and slippery pitch.