A fighter has been pulled off Saturday's UFC on FOX 20 card due to a potential compliance issue with the UFC's anti-doping violation.

George Sullivan is out of his fight with Hector Urbina, the UFC announced Thursday, after voluntarily notifying USADA about a potential compliance issue with regards to the UFC's anti-doping policy, the UFC announced. The UFC said in a release that Sullivan was removed "out of an abundance of caution" and USADA will conduct an investigation on the matter.

Sullivan, 35, has not failed a drug test, nor is he facing a potential anti-doping policy violation at this time. According to the USADA website, Sullivan has been tested twice this year.

Urbina, 28, will still weigh-in Friday in case he is needed as backup opponent for another bout on Saturday's card in Chicago. If he won't be needed, Urbina will be rebooked for another event in the near future.

Sullivan (17-5, 1 NC) is coming off a first-round knockout loss to Alexander Yakovlev at UFC on FOX 18 in January. The New Jersey native sports a 3-2 record in the UFC after an excellent run in Cage Fury Fighting Championships and Ring of Combat. Sullivan, has been a pro MMA fighter for 10 years.

The UFC's full release is below: