Some significant news broke courtesy on Monday, as Golden Boy Promotions announced in a statement that their fighter, Canelo Alvarez (49-1-2, 34 KOs), tested positive for a banned substance in a Voluntary Anti-Doping Association (VADA) drug test, just two months out from his highly anticipated rematch with middleweight champion Gennady Golovkin (37-0-1, 33 KOs).

The full press release is as follows:

As part of the voluntary testing program that Canelo Alvarez insisted on ahead of his May 5 fight, one of his results came back positive for trace levels of Clenbuterol, consistent with meat contamination that has impacted dozens of athletes in Mexico over the last years. As Daniel Eichner, Director of SMRTL, the WADA-accredited lab that conducted the tests stated in his letter today, “These values are all within the range of what is expected from meat contamination.” Upon receiving this information, Golden Boy immediately notified the Nevada State Athletic Commission and Gennady Golovkin’s promoter, Tom Loeffler. As has been planned, Canelo will immediately move his training camp from Mexico to the United States and will submit to any number and variety of additional tests that VADA deems necessary ahead of and after May 5. Added Canelo: ”I am an athlete who respects the sport and this surprises me and bothers me because it had never happened to me. 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.” Canelo has tested clean dozens of times over the course of his previous 12 fights.

Clenbuterol is often used to treat asthma and other breathing problems, but can help with weight loss and increase muscle mass, and is considered a performance-enhancing drug.

This is the first time that the Mexican superstar has tested positive in his 13-year professional career.

The issue with “tainted meat” causing drug test failures for clenbuterol have also happened several times among UFC fighters. Among those who ultimately had “no fault” outcomes (thus no suspension from USADA) include bantamweight Ning Guangyou of China, as well as Mexico’s Augusto Montano, Mexican flyweight contender Brandon Moreno, and Chinese welterweight Li Jingliang.

The World Anti-Doping Agency (WADA) had issued a warning about contaminated meat in China and Mexico way back in 2011, and the National Football League sent out a notice to its players just two years ago.

In the boxing world, Francisco Vargas popped for clenbuterol before his June 2016 fight vs. Orlando Salido. The California State Athletic Commission gave him a provisional license, and he was permitted to compete. Vargas would pass additional drug tests and receive no suspension.

Not everyone has been able to avoid a ban, however. Australian heavyweight Lucas Browne was stripped of his WBA title and suspended for six months after positive A- and B-samples of the drug. Browne denied knowingly ingesting the substance. Former UFC fighter Francisco Rivera used the tainted meat defense, but was given a four-year ban after falsifying evidence to support his claim.

Going back to Canelo’s failed drug test, it’s been confirmed that Canelo vs. GGG 2 is still on course to happen on May 5th in Las Vegas, Nevada... provided we don’t see this situation take a turn for the worse.