Middleweight boxer Canelo Alvarez has tested positive for a banned drug, and his promoters blame contaminated meat.
A voluntary test showed Alvarez had traces of clenbuterol. A statement from Golden Boy Promotions said the amount was consistent with meat contamination that has impacted athletes in Mexico and China.
Daniel Eichner, director of the World Anti-Doping Agency-accredited laboratory that conducted the test, wrote Monday: "These values are all within the range of what is expected from meat contamination."
Alvarez is scheduled for a rematch with middleweight champion Gennady Golovkin on May 5 in Las Vegas, a highly anticipated fight after their draw last year.
Alvarez will move his training camp from Mexico to the United States and submit to additional tests, Golden Boy said.
Clenbuterol, often used by asthmatics, has fat burning properties and athletes have been known to use it to help them drop body fat and weight quickly. Among those who have tested positive for it are baseball players Raul Mondesi and Guillermo Mota, champion cyclist Alberto Contador, and a number of participants in the 2008 Beijing Olympics.
"I am an athlete who respects the sport and this surprises me and bothers me because it had never happened to me," Alvarez said. "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."
Alvarez, 27, of Mexico, and Golovkin, from Kazakhstan, are among the best active boxers. Alvarez, whose given name is Saul, is 49-1-2 with 34 knockouts. He relinquished his previous belts before meeting Golovkin last September, when Alvarez won on one card 118-110, lost 115-13 on another and third judge had it 114-114.
"It's tough to comment on it, we're waiting for the Nevada commission to do their due diligence," Tom Loeffler, Golovkin's promoter, told The Associated Press. "We would like the fight to continue if there is any way for that to happen.
"Triple G always has wanted to undergo testing because he hits so hard and is so well-conditioned, he didn't want there to be any questions on his side. He had wanted both fighters to undergo testing to make for a level playing field as much as possible."