UFC light heavyweight champion Jon Jones has entered a drug rehabilitation facility after testing positive for the main metabolite of cocaine.
The UFC issued a statement supporting the 27-year-old Jones on Tuesday, three days after he defeated Daniel Cormier to cement his reputation as the world's best pound-for-pound mixed martial artist.
"I am proud of Jon Jones for making the decision to enter a drug treatment facility," UFC President Dana White said.
Jon Jones celebrates between rounds during a light heavyweight title mixed martial arts bout against Daniel Cormier on 3 January
"I'm confident that he'll emerge from this program like the champion he truly is."
Jones (21-1) was tested by the Nevada Athletic Commission last month heading into his title defense against Cormier at UFC 182 in Las Vegas.
Benzoylecgonine is not banned by World Anti-Doping Agency guidelines for out-of-competition use, so Jones wasn't penalized or suspended before he defeated Cormier by unanimous decision.
Jones was given the random test on 4 December, and the Nevada commission still could impose disciplinary measures on the fighter.
The UFC also could discipline Jones, but showed no indication of such plans in its initial statement.
"While we are disappointed in the failed test, we applaud him for making this decision to enter a drug treatment facility," the UFC's statement read.
"Jon is a strong, courageous fighter inside the octagon, and we expect him to fight this issue with the same poise and diligence. We commend him on his decision, and look forward to him emerging from this program a better man as a result."
Reebok also stood behind Jones, who signed with the company less than a month ago after a long-standing deal with Nike.
"We commend Jon for taking the necessary steps to address this issue, and we will support him in any way we can," Reebok announced in a statement. "The status of Jon's relationship with Reebok has not changed."
Through his attorney, Jones issued a statement to Yahoo Sports apologising to his family, including his fiancee and their four daughters.
The upstate New York native, who now lives and trains in Albuquerque, New Mexico, is the brother of New England Patriots defensive end Chandler Jones and Indianapolis Colts defensive end Arthur Jones.
The positive drug test is the latest twist in a tumultuous career for Jones, a former junior college wrestler who has risen to the top of his sport.
Jones' impressive victory over the previously unbeaten Cormier was his eighth consecutive title defense since winning the belt in March 2011, when he became the youngest champion in UFC history at 23. Jones has evolved into one of the most dominant champions in UFC history, with athleticism and creativity that have allowed him to dominate almost every contender.
He also has developed a reputation for quirkiness and arrogance that have turned him into a villain to many MMA fans — and even occasionally to White, who infamously ripped Jones in 2012 after he refused to take on a replacement opponent on short notice, forcing the promotion to cancel UFC 151.
Jones was arrested and charged with driving while intoxicated in Binghamton, New York, in 2012 after smashing his Bentley into a pole. He eventually pleaded guilty and avoided jail time.
Jones and Cormier were involved in a brawl in a casino lobby in August while promoting their bout, with Jones rushing Cormier off the stage and into a crowd.
The Nevada commission fined both fighters and ordered them into community service.