- Jon Jones bout removed from UFC 200 fightcard
- MMA fighter records "potential anti-doping violation"
Jones, 28, was due to fight Daniel Cormier for the light-heavyweight title in Las Vegas Saturday.
"The UFC organization was notified tonight that the U.S. Anti-Doping Agency (USADA) has informed Jon Jones of a potential Anti-Doping Policy violation stemming from an out-of-competition sample collection on June 16, 2016," said a UFC statement released late Wednesday.
While noting that Jones has the right to "a full fair legal review," the statement added it would not be possible to conclude that process before Saturday's big event.
As a result, the fight has been removed from the card. The three-round heavyweight matchup between Brock Lesnar and Mark Hunt will now become the main event at UFC 200, one of the biggest promotions in the sport's history.
The Jones-Cormier bout was initially elevated to the top of the UFC 200 bill after the much-anticipated rematch of Irishman Conor McGregor and Nate Diaz was canceled in April.
Jones became the youngest UFC champion when he claimed the light-heavyweight title in 2011 at the age of just 23.
However, he was stripped of that title and suspended from the UFC in April 2015 following a criminal hit-and-run charge relating
to an incident in Albuquerque, New Mexico.
Earlier in 2015, Jones entered rehab for a day after testing positive for cocaine in a test administered by the Nevada Athletic Commission.
Although Jones defeated Cormier in January 2015, Cormier won the UFC light-heavyweight title during his rival's suspension from the sport.
Jones' UFC suspension came to an end in September last year and he is ranked as the No. 1 pound-for-pound fighter in the UFC's rankings.