Lightweight Thiago Tavares tested positive for the anabolic steroid Drostanolone, following his Jan. 19 loss in Rio de Janeiro, UFC announced Wednesday on its website.
Dana White has opted not to speak with the recently retired light heavyweight fighter Stephan Bonnar since the fighter's positive test results were revealed.
Heavyweights Shane Carwin and Roy Nelson have passed prefight drug tests for their Dec. 15 bout, Nevada State Athletic Commission executive director Keith Kizer said Friday.
Recently retired light heavyweight Stephan Bonnar and heavyweight Dave Herman failed their respective UFC 153 postfight drug tests, a source told ESPN.com on Friday.
Former UFC middleweight contender Nate Marquardt has signed a contract with Strikeforce, Fuel TV reported Tuesday night.