Gilbert Burns tested positive for the coronavirus and will no longer fight welterweight champion Kamaru Usman at UFC 251, according to Mike Bohn of MMA Junkie.
Burns and Usman won't fly to Abu Dhabi on Friday night, and the current plan is to reschedule the bout for a later date, according to MMA Junkie's John Morgan.
Usman, who hasn't lost since 2013, last fought in December at UFC 245 against Colby Covington where he defended his title for the first time. Meanwhile, Burns extended his winning streak to six after beating former champ Tyron Woodley in May.
The featherweight title rematch between Max Holloway and new champion Alexander Volkanovski will now headline UFC 251.
"I feel like we were already the main event," Holloway told Morgan.
Holloway will be trying to get back in the win column after dropping the title in December. Volkanovski, who beat Holloway by unanimous decision, is 8-0 in the UFC.
The stacked UFC 251 card also features Petr Yan and Jose Aldo meeting for the vacant bantamweight title following former champion Henry Cejudo's abrupt retirement in May.