Anderson Silva's will not be facing Kelvin Gastelum at UFC 212 in Rio de Janeiro, Brazil as the latter was flagged for potentially testing positive for marijuana metabolites.

Gastelum had asked for a bout with "The Spider" following his win over Vitor Belfort at UFC Fortaleza on 11 March and it was confirmed to take place at the pay-per-view on 3 June.

However, the UFC pulled the 25-year-old out of the card following an in-competition drug test conducted by the US Anti-Doping Agency (USADA).

The drug test coincided with Gastelum's victory over Belfort as he was flagged for "Carboxy-Tetrahydrocannabinol (Carboxy-THC) which is a metabolite of marijuana and/or hashish."

As a result of the potential anti-doping violation, the Mexican-American, who has a 14-2 record in MMA, has been placed in a provisional suspension.

While Gastelum will be given his full and fair due process rights, he will now be replaced by another fighter on the card as the case opened up with UFC 212 so close. As for a replacement opponent for Silva, Yoel Romero notably signaled his intentions of facing the former middleweight champion and may be a potential contender.

It comes as a huge blow to Gastelum who had previously stated his goals of winning both the middleweight and the welterweight titles, which will be made much harder now.

"The UFC organization was notified today that the U.S. Anti-Doping Agency (USADA) informed Kelvin Gastelum of a potential Anti-Doping Policy violation involving Carboxy-Tetrahydrocannabinol ("Carboxy-THC") which is a metabolite of marijuana and/or hashish, above the decision limit of 180 ng/mL, stemming from an in-competition sample collected in conjunction with his recent bout in Fortaleza, Brazil on March 11, 2017," the official UFC statement said.

Kelvin Gastelum
Gastelum following his win over Vitor Belfort at UFC Fortaleza Getty

"USADA, the independent administrator of the UFC Anti-Doping Policy, will handle the results management and appropriate adjudication of this case involving Gastelum, as it relates to the UFC Anti-Doping Policy and future UFC participation. Because the Brazilian MMA Athletic Commission (CABMMA) was the regulatory body overseeing the fight in Fortaleza and has licensing jurisdiction over Gastelum, USADA will work to ensure that the Commission has the necessary information to determine its proper judgment of Gastelum's potential anti-doping violation. Additional information will be provided at the appropriate time as the process moves forward."