Anderson Silva has been removed from UFC's debut event in mainland China after he failed an out-of-competition drug test.
Former middleweight champion Silva, 42, had been slated to headline the Shanghai show in a fortnight against Kelvin Gastelum, but the Brazilian will not feature due to the potential doping violation.
While he is deemed innocent until his B sample has been tested, the proximity to the China card means he has been immediately removed from the event, with the UFC now seeking a new opponent for Gastelum.
It marks the second time that Silva has had a bout against the American cancelled.
Their scheduled meeting at UFC 212 in June was called off after Gastelum tested positive for marijuana.
A UFC statement read: "The UFC organization was notified today that the U.S. Anti-Doping Agency (USADA) has informed Anderson Silva of a potential Anti-Doping Policy violation stemming from an out-of-competition sample collected on October 26, 2017.
"As a result, Silva has been provisionally suspended by USADA. Due to the proximity of Silva's upcoming scheduled bout at UFC Fight Night, Shanghai, China on November 25, 2017 against Kelvin Gastelum, Silva has been removed from the card and UFC is currently seeking a replacement."
Silva has previously tested positive for anabolic steroids around his UFC 183 bout against Nick Diaz. The veteran claimed the positive results were a result of taking a tainted sexual-enhancement substance. He was banned for a year.
The UFC added on Friday: "USADA, the independent administrator of the UFC Anti-Doping Policy, will handle the results management and appropriate adjudication of this case involving Silva.
"Under the UFC Anti-Doping Policy, there is a full and fair legal process that is afforded to all athletes before any sanctions are imposed. Additional information will be provided at the appropriate time as the process moves forward."