PSV Eindhoven defender Francisco Rodriguez and starting goalkeeper Guillermo Ochoa were among five players dropped from Mexico's Gold Cup squad on Friday after testing positive for a banned substance.
Decio de Maria, the secretary general of the Mexican football federation, said Ochoa and Rodriguez - veterans of the 2010 World Cup - tested positive for clenbuterol. Also testing positive were defender Edgar Duenas and midfielders Christian Bermudez and Antonio Naelson.
De Maria said he believes the positive results come from the players eating contaminated beef. Last July, Tour de France champion Alberto Contador also tested positive for the banned anabolic agent and said he consumed the drug in tainted beef.
Hector Gonzalez Inarritu, Mexico's team director, said after the team's 5-0 win over Cuba on Thursday that Mexican government officials and the players will travel to Los Angeles on Friday for further testing.
"We have members of the secretary of agriculture in Mexico trying to find out what happened to the meat, what they ate and when they ate it," Gonzalez Inarritu said. "It seems like it was a small piece of meat the five players ate. This investigation is very through at the moment and we're trying to get a happy ending."
Until an investigation is completed, the Mexican players won't be able to play.
"Now comes the tough part, taking the players off the squad and opening an investigation," De Maria said. "Meanwhile, it is a disagreeable moment to take this kind of decision, but we have to take responsibility."
The latest potential doping scandal has the potential to dramatically affect the Gold Cup, the championship of North and Central America and the Caribbean. Mexico is the defending champion and one of the favorites again this year along with the United States.
"Not having all the players hurt," coach Jose Manuel De La Torre said after Mexico had little difficulty with overmatched Cuba, "but we will be waiting for CONCACAF result and what they decide."
CONCACAF spokesman Ben Spencer said the governing body would meet in a conference call Friday to decide possible sanctions for Mexico and if the team will be able to replace the suspended players. Spencer said Mexico would not lose the three points it received for beating El Salvador 5-0 in the opening match of Group A on Sunday.
"We're still getting information as it comes down," Spencer said. "(Mexico) has chose to separate the players from the team."
Clenbuterol is used in some countries to treat breathing disorders, but also has been used as a weight-loss drug. De Maria said the players were tested on May 21, but the results weren't revealed until Wednesday.
"The substance that they tested positive for is illegal in Mexico, so it is not found at your common pharmacy," said Mexico team doctor Jose Luis Serrano. "We've never given any of the players this type of medicine.
"It's unfortunate, but this drug is very common in (in cattle) in Mexico. ... We could do a test on ourselves and likely come out with the same result."
Teams were able to bring a squad 23 players to the Gold Cup. Ricardo Osorio already was sent home with an illness, so Mexico was down to 17 eligible players against Cuba at Bank of America Stadium. Jonathan Orozco and Alfredo Torrado are the other goalkeepers on the squad.
Spencer said a decision on whether Mexico would be able to call up replacement players likely would be made before Sunday's final group match against Costa Rica.
Spencer said two Mexican players - Pablo Barrera and Efrain Juarez - passed random drug tests after Sunday's game. The five suspended players were not tested.
"It's completely an accident," Gonzalez Inarritu said. "We're calm. We're not worried."
The suspensions dampened increased enthusiasm for Mexico's team. Javier Hernandez, who scored 20 goals for Manchester United this season, has scored five goals in two games.