Luis Nery, who won a bantamweight world title by fourth-round knockout of Shinsuke Yamanaka on Aug. 15 in Kyoto, Japan, has failed a Voluntary Anti-Doping Association-administered drug test, putting the victory and title in jeopardy.
The WBC announced on Wednesday that it was notified by VADA, which administers the sanctioning organization's mandatory Clean Boxing Program, that Nery had an adverse test for the banned substance zilpaterol, which is typically used to increase the size of cattle.
The WBC said the Clean Boxing Program "will begin the process according to its protocol and will provide additional information during the process."
The end result could see the outcome of the fight overturned to a no decision, with the title returned to Yamanaka.
Nery, 22, of Mexico, was the mandatory challenger when he went to Yamanaka's home country to challenge for the 118-pound world title. He relentlessly battered Yamanaka into a fourth-round knockout, ending -- at least for the time being -- Yamanaka's long reign and a shot at Japanese boxing history.
Yamanaka, 34, had made 12 successful title defenses and was bidding for No. 13, which would have tied the Japanese record for world title defenses set by Hall of Fame former junior flyweight champion Yoko Gushiken, who established the mark in 1980.
Although Yamanaka (27-1-2, 19 KOs) got off to a solid start, controlling most of the action for the first two rounds thanks to his steady jab, Nery (24-0, 18 KOs), who was fighting outside of Mexico for the first time, took over in the third round.
In the fourth round, he continued to pound fellow southpaw Yamanaka. He landed a powerful left hand that sent Yamanaka into the ropes and continued to blast away. He had Yamanaka in tremendous trouble and as he continued to rain punches on him, Yamanaka's trainer entered the ring to stop the fight. Referee Michael Griffin waved it off at 2 minutes, 29 seconds.