The career of former two-division titleholder Joan Guzman has sunk further into an abyss. Guzman tested positive for Furosemide, a diuretic on Nevada's banned substance list, following a second-round knockout of Jason Davis on Dec. 11 on the Amir Khan-Marcos Maidana undercard at Mandalay Bay, according to Nevada State Athletic Commission executive director Keith Kizer. Golden Boy promotions has also released Guzman from his promotional contract, CEO Richard Schaefer told ESPN.com. Diuretics can be used as masking agents for steroids and are also used to help with weight loss. Guzman has a history of failing to make weight. For the second fight in a row -- and at least the third time -- Guzman did not make the contract weight. He was supposed to face Davis at a maximum weight of 141 pounds but came in at 144. In his previous fight in March, Guzman was supposed to weigh 135 pounds to challenge Ali Funeka for a vacant lightweight title. But Guzman showed up a whopping nine pounds overweight. The fight went on anyway. Guzman (31-0-1, 18 KOs) won a split decision, but the title remained vacant. Read more: http://sports.espn.go.com/sports/boxing/news/story?id=6036464