Lineal middleweight champion Canelo Alvarez tested positive for trace levels of the banned substance Clenbuterol ahead of his May 5 pay-per-view rematch with unified champion Gennady Golovkin in Las Vegas. 

Golden Boy, Alvarez's promoter, released a statement Monday claiming the positive test was the byproduct of meat contamination, which the promotion claims has impacted dozens of athletes in Mexico in recent years. 

"These values are all within the range of what is expected from meat contamination," said Daniel Eichner, director of the Sports Medicine Research and Testing Laboratory, a lab accredited by the World Anti-Doping Agency, that conducted the tests. 

According to the statement, Golden Boy alerted both the Nevada State Athletic Commission and Tom Loeffler, the promoter of Golovkin, upon finding out about the failed test. There is no immediate word from either promoter as to what this will do to affect the scheduled fight.  

"I am an athlete who respects the sport and this surprises me and bothers me because it had never happened to me," Alvarez said in the statement. "I will submit to all the tests that require me to clarify this embarrassing situation and I trust that at the end the truth will prevail."

Golden Boy said Alvarez, 27, will move his training camp from Mexico to the United States immediately and will submit to any additional tests deemed necessary by the Voluntary Anti-Doping Agency, a partner in WBC's Clean Boxing Program. The promotion also insisted Alvarez has tested clean "dozens of times" over the course of his previous 12 fights.

WBC president Mauricio Sulaiman tweeted support for Alvarez's history of being clean and said WBC would be consistent in following protocol in terms of investigating the details. Sulaiman also noted what he called "a public health problem in Mexico" that needs to be analyzed before making conclusions. 

Alvarez (49-1-2, 34 KOs) fought to a disputed draw last September against Golovkin (37-0-1, 33 KOs), holder of the WBA and IBF titles, in a fight most observers felt the 35-year-old GGG had won. 

"We're not really going to comment until we get more detail from VADA and the commission. We'll reserve comment," Loeffler told ESPN. "But Gennady has always insisted on VADA testing for any of his fights. He punches so hard that [trainer] Abel [Sanchez] wanted nobody to have any doubt about his training program. Gennady feels very strongly about a clean sport and level playing field for both guys. He can't comment on this test specifically, but that's his position. It's premature to say anything more without knowing all of the details."

Former junior lightweight titleholder Francisco Vargas tested positive for Clenbuterol in 2016 ahead of his all-action brawl with Orlando Salido. After a similar defense of having consumed contaminated beef, Vargas was allowed to fight on a probationary basis after being issued a temporary license by the California State Athletic Commission. 

Hall of Famer Erik Morales also tested positive for the drug ahead of his 2012 loss to Danny Garcia in their junior welterweight title rematch in Brooklyn, New York, but was allowed to compete in the fight. Like Alvarez, both Vargas and Morales were promoted by Golden Boy. 

As a performance-enhancing drug, Clenbuterol is used to increase aerobic capacity, burn fat and preserve muscle. It is also used by sufferers of breathing disorders as a decongestant and bronchodilator.