Welterweight title challenger Gilbert Burns is out of the UFC 251 main event after testing positive to COVID-19. Burns (19-3) was supposed to fight champion Kamaru Usman (16-1) next weekend at the fight promotion's first event at Fight Island on Yas Island, Abu Dhabi, United Arab Emirates.  He trained for the bout in Florida and traveled from The Sunshine State to Las Vegas.  He was tested upon arrival in Las Vegas and the test results came back positive.  His brother, Herbert Burns, and coach Greg Jones also tested positive for the virus.  TRENDING > Conor McGregor offers condolences on the loss of Khabib Nurmagomedov’s father The three were quarantined and did not board the chartered flight to the Middle East.  With Burns out of the event, the fight card now features two world title bouts.  Featherweight champion Alexander Volkanovski  and former champion Max Holloway rematch and former featherweight champion Jose Aldo and Petr Yan face off for the vacant bantamweight title.  It's unclear if Burns will be replaced or if Usman will be pulled from the event as well.