Erik Morales fails drug test

Former four-division titleholder Erik Morales, due to challenge Danny Garcia in a rematch for his junior welterweight belts Saturday night, failed a random drug test administered by the U.S. Anti-Doping Agency.

However, two sources involved with the card said the fight is expected to go on Saturday. It headlines a Showtime-televised card featuring four world title bouts at the new Barclays Center in Brooklyn, N.Y.

The reason the fight has not been called off, according to one of the sources, is because Morales' "A" sample tested positive, but the results of the "B" sample test likely won't be available until after the fight.

"As far as I know, the fight is going on," one of the sources told ESPN.com. "There is nothing that can be done to stop it" because the "B" sample test result has not yet been disclosed.

According to one of the sources, Morales tested positive for the banned substance clenbuterol, which is typically used for breathing disorders but also is used as a weight-loss aid. Cyclist Alberto Contador of Spain was banned from professional cycling for two years because he tested positive for clenbuterol during the 2010 Tour de France.

In March, Morales failed to make the 140-pound weight limit for a title defense against Garcia in Houston. Because he did not make weight, Morales was stripped of his world title. The fight went on and Garcia outpointed him the next night to win the vacant belt. They are meeting again because Morales exercised the rematch clause he had in his contract after allowing Garcia an interim bout -- which he took in July and knocked out Amir Khan to unify titles.

USADA discussed the test results with the fighter camps, Golden Boy and the New York State Athletic Commission during a teleconference on Thursday.

"(USADA) said it could be a false positive," one of the sources with knowledge of the disclosure said. "But from what I understand, they won't know until the test on the 'B' sample comes back, but that probably won't be until after the fight."

Golden Boy Promotions chief executive Richard Schaefer, who is promoting the show, was not available for comment but told Sports Illustrated that Morales' test had "irregularities" and that "USADA has now started the process, which will play out. There is not going to be a rush to judgment. Morales is a legendary fighter. And really, nobody deserves a rush to judgment. You are innocent until proven guilty."

In some fights it has promoted, Golden Boy has announced that the fighters were undergoing USADA random blood and urine tests leading up to them. The fact that Garcia and Morales were using USADA had not been disclosed until the positive test.

This is the fifth time this year that a high-profile fighter has had a positive drug test. Junior welterweight titlist Lamont Peterson tested positive for synthetic testosterone, causing his rematch with Khan to be canceled -- which is why Khan wound up facing Garcia. Former welterweight titlist Andre Berto tested positive for a steroid, causing his rematch with Victor Ortiz to be canceled.

Former light heavyweight champ Antonio Tarver fought Lateef Kayode to a draw in a cruiserweight fight but tested positive for a steroid after it. He was suspended for a year by the California State Athletic Commission, fined and had the result of the fight overturned to a no-decision.

Following his middleweight world title loss to Sergio Martinez last month, Julio Cesar Chavez Jr. tested positive for marijuana, his second failed post-fight drug test since 2009.

Peterson and Berto, who were both fighting on Golden Boy cards, were using the Voluntary Anti-Doping Association to conduct their testing. Tarver was caught by the standard California commission testing.