By Rick Reeno

Top Rank, who promote middleweight Julio Cesar Chavez Jr., have confirmed to BoxingScene.com that the Mexican star tested positive for marijuana following Saturday's twelve round unanimous decision loss to Sergio Martinez. The fight took place at the Thomas & Mack Center in Las Vegas.

BoxingScene was provided with the following statement from Top Rank - "Top Rank is reviewing the situation. Julio Cesar Chavez Jr. will have the opportunity to explain about the situation to the Nevada State Athletic Commission."

Nevada State Athletic Commission Executive Director Keith Kizer has confirmed to BoxingScene.com's David Greisman that Top Rank's statement accurately represents a conversation he had with the promoter on Tuesday afternoon.

This marks the second time that Chavez tested positive for a banned substance in Nevada. In 2009, he tested positive for Furosemide, a diuretic, after his win over Troy Rowland. The official result was changed to a no-decision. Chavez was fined $10,000 and suspended for seven months. He faces similar punishment with the latest incident.

Martinez (50-2-2, 28KOs) dominated Chavez (46-1-1, 32KOs) for nearly eleven rounds, before Chavez badly hurt Martinez and scored a knockdown in the twelfth. Martinez survived to win a lopsided decision with scores of 118-109, 117-110 and 118-109.