Julio Cesar Chavez Jr. tests positive for banned substance after Sergio Martinez fight

Julio Cesar Chavez Jr. (above) tested positive for a banned substance -- reportedly marijuana -- after Saturday's fight with Sergio Martinez in Las Vegas. (AP)

Julio Cesar Chavez Jr. (above) tested positive for a banned substance -- reportedly marijuana -- after Saturday's fight with Sergio Martinez in Las Vegas. (AP)

Former middleweight titleholder Julio Cesar Chavez Jr. tested positive for a banned substance following Saturday's unanimous-decision defeat to Sergio Martinez. Chavez’s promoter, Top Rank, confirmed the positive test.

Top Rank's Carl Moretti confirmed the positive test was for marijuana.

"Top Rank is reviewing the situation,” Top Rank publicist Lee Samuels said in a statement. “Julio Cesar Chavez Jr will have the opportunity to explain this situation to the Nevada State Athletic Commission."

The positive test is the second for Chavez in Nevada. In 2009, Chavez tested positive for Furosemide, a known diuretic that helps with weight loss, after his win over Troy Rowland. Chavez was suspended for seven months and fined $10,000 by the commission. The official result was changed to a no-contest.

Last week, Chavez cited that positive test as one of the turning points of his career.

“I thought about it, and I said, 'What am I doing here? Do I need to be serious about this?’” Chavez said. “‘Do I really want this? How much do I want it?'”

NSAC executive director told SI.com there is no mandatory suspension length for a second positive test. Kizer said any violation can result in a fine of up to 100 percent of the fighter’s purse -- Chavez was guaranteed $3 million against Martinez -- and/or a one-year suspension.

The positive test is the latest act of immaturity from the 26-year old Chavez. Last January, Chavez was arrested for suspicion of DUI. He pleaded no contest and was sentenced to probation. Before teaming up with Hall of Fame trainer Freddie Roach, Chavez had a reputation for being lazy in the gym. Though he seemed to shed that reputation over the last year, in the weeks before the fight with Martinez, Chavez routinely skipped out on training sessions, often preferring to work out at home late at night rather than at the gym.

Roach said he will continue to work with Chavez but that “the first day he misses something, I’m going home.”

-- Chris Mannix