Lucas Browne’s storybook ending to his heavyweight title bout with Ruslan Chagaev doesn’t look as if it will end well after all.

Browne failed a post-fight drug test for his March 5 bout against Chagaev, a source confirmed. ESPN.com first reported the news on Monday. The news tarnishes Browne’s dramatic 10^th-round stoppage to win what the WBA calls its “regular” title, rising from a sixth-round knockdown to do so.

Browne (24-0, 21 knockouts) tested positive for the banned weight-loss drug Clenbuterol in a urine test, the source confirmed, and will likely be stripped of the title he won in Grozny, Russia. THE RING doesn’t recognize “regular” titleholders unless there is no “super” champion in place. Tyson Fury is the actual WBA champ.

The WBA didn’t immediately return an email seeking comment on its plans in the wake of the news. Browne responded on his personal Twitter account, writing, “I don’t understand today’s news, and I’m seeking legal advice…”

Both fighters were administered testing by the Las Vegas-based Voluntary Anti-Doping Association (VADA). Browne’s “A” urine sample contained traces of Clenbuterol, the source confirmed. Browne has not yet requested analysis of his ‘B’ sample, the source said. ESPN.com obtained a letter from VADA president Dr. Margaret Goodman detailing the positive drug test to fight organizers.

“This letter is to advise you that the ‘A’ sample urine specimen number 2998060 collected from Lucas Browne … has been analyzed for anabolic agents, diuretics, beta-2 agonists and stimulants,” she wrote, according to ESPN.com. “The results of the analysis are as follows: Adverse. Urine specimen contains Clenbuterol.” Browne can request analysis of the “B” sample at “his expense,” the letter said.

Dr. Goodman declined comment when contacted by RingTV.com on Monday other than to confirm VADA was responsible for the drug testing of both fighters and does not release its results to the public.

“All I can say at this time is we tested both Mr. Chagaev and Mr. Browne the week of the fight and post-fight per a request from representatives of the BDB (German Boxing Commission),” Dr. Goodman wrote in an email. “VADA does not release results to the public, so any information regarding results would have to be obtained form the commission, the athletes or their representatives.”

Before news of the positive drug test, Browne, 36, was in line to face mandatory challenger Fres Oquendo by June as part of the WBA’s heavyweight tournament to consolidate its three titles. Luis Ortiz is the WBA’s “interim” titleholder.

Clenbuterol is a popular weight-loss drug among bodybuilders, though boxers have also used it. Erik Morales reportedly tested positive for Clenbuterol twice before a rematch with Danny Garcia in 2012. Morales claimed the positive test was the result of eating tainted meat.