Mexico's director of national teams Hector Inaturri has backed the five players suspended for a doping offence to prove their innocence.
The quintet - Antonio Naelson, Christian Bermudez, Edgar Duenas, Francisco Rodriguez and Guillermo Ochoa - tested positive for clembuterol at a pre-Gold Cup training camp and were immediately ruled out of last night's 5-0 win over Cuba.
Inaturri believes contaminated meat may have be behind the results and he will accompany the players when they travel to Los Angeles today for further tests at UCLA.
He said: "We will wait for all the results and see what the department of agriculture in Mexico finds in the meat we used.
"We'll expect the results which I am sure will be negative."
Team physician Dr Jose Luis Serrano added: "There is no remote possibility that this happened because of a supplement.
"I think there is no precedent that has five positive tests with only one substance in one event."
Mexico have asked CONCACAF if they can replace the suspended players.
CONCACAF general secretary Chuck Blazer said a meeting of the confederation's national teams committee, which also serves as the organising committee of the Gold Cup, will be convened via conference today to consider the situation.