Top UFC middleweight contender Vitor Belfort is coming off a stellar knockout over former Pride and Strikeforce champ Dan Henderson at UFC Fight Night 32 and he claims he did it without the full aid of testosterone replacement therapy.

"My (testosterone) levels were low in my last fight," Belfort told MMAFighting.com during a media scrum in his gym in Rio de Janeiro, Brazil. “I have all the exams to prove that I have a disease. It’s simple."

Belfort is generally viewed by pundits as what is wrong with TRT usage in MMA, due to his lean, muscular physique and career renaissance at 36 years old.

The hard-hitting Brazilian is definitely in the running for “Fighter of the Year” in 2013, knocking out perennial contender Michael Bisping, ex-Strikeforce champ Luke Rockhold and now Henderson (who had never been KO’ed) before.

“The Phenom” boasts a 5-1 mark at middleweight, with his only loss coming at the hands of long-time middleweight champ Anderson Silva back at UFC 126 in February 2011.

UFC President Dana White has indicated that barring an injury or “something crazy,” Belfort will fight the winner of Anderson Silva vs. Chris Weidman II, a middleweight title bout which takes place at UFC 168 next month.

Weidman unseated Silva at UFC 162 in July, becoming the first competitor to KO “The Spider” in 38 professional mixed martial arts contests.

Should Weidman, who is undefeated at 10-0, win again, Belfort says he has no qualms about fighting again in the United States, although that hasn’t happened since August 2011.

"Chael Sonnen has a license to fight in Vegas, and I’m doing everything by the book," Belfort said. "I have all the exams to prove it."

Like Belfort, Sonnen failed a drug test years ago for elevated levels of testosterone, and as Belfort points out, “The American Gangster” has since competed in Las Vegas since then.